Firebird Language Reference Scheleton
Table of Contents List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi CHAPTER 1 Using the Firebird Language Reference Topics covered in this book CHAPTER 2 SQL Statement and Function Reference Database object naming conventions Statement list Function list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Datatypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Error handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Using statement and function definitions . . . . . . . . . . . . . 21 ALTER DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . . 22 ALTER DOMAIN . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 ALTER EXCEPTION . . . . . . . . . . . . . . . . . . . . . . . . . 25 ALTER INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 ALTER PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . 27 ALTER TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ALTER TRIGGER . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 AVG( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 BASED ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 BEGIN DECLARE SECTION . . . . . . . . . . . . . . . . . . . . . 39 CAST( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 CLOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 CLOSE (BLOB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 COMMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 CONNECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 COUNT( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 CREATE DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . 49 CREATE DOMAIN . . . . . . . . . . . . . . . . . . . . . . . . . . 52 iii
CREATE EXCEPTION . . . . . . . . . . . . . . . . . . . . . . . . 57 CREATE GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . 58 CREATE INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 CREATE PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . 61 CREATE ROLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 CREATE SHADOW . . . . . . . . . . . . . . . . . . . . . . . . . . 69 CREATE TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 CREATE TRIGGER . . . . . . . . . . . . . . . . . . . . . . . . . . 80 CREATE VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 DECLARE CURSOR . . . . . . . . . . . . . . . . . . . . . . . . . 90 DECLARE CURSOR (BLOB) . . . . . . . . . . . . . . . . . . . . . 92 DECLARE EXTERNAL FUNCTION . . . . . . . . . . . . . . . . . 93 DECLARE FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . 95 DECLARE STATEMENT . . . . . . . . . . . . . . . . . . . . . . . 97 DECLARE TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 DELETE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 DESCRIBE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 DISCONNECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 DROP DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . 102 DROP DOMAIN . . . . . . . . . . . . . . . . . . . . . . . . . . 103 DROP EXCEPTION . . . . . . . . . . . . . . . . . . . . . . . . . 104 DROP EXTERNAL FUNCTION . . . . . . . . . . . . . . . . . . 105 DROP FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 DROP INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 DROP PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . 108 DROP ROLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 DROP SHADOW . . . . . . . . . . . . . . . . . . . . . . . . . . 109 DROP TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 DROP TRIGGER . . . . . . . . . . . . . . . . . . . . . . . . . . 111 DROP VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 END DECLARE SECTION . . . . . . . . . . . . . . . . . . . . . 112 EVENT INIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 EVENT WAIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 iv
EXECUTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 EXECUTE IMMEDIATE . . . . . . . . . . . . . . . . . . . . . . 117 EXECUTE PROCEDURE . . . . . . . . . . . . . . . . . . . . . . 118 FETCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 FETCH (BLOB) . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 GEN_ID( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 GRANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 INSERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 INSERT CURSOR (BLOB) . . . . . . . . . . . . . . . . . . . . . 129 MAX( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 MIN( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 OPEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 OPEN (BLOB) . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 PREPARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 REVOKE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 ROLLBACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 SELECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 SET DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 SET GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . 148 SET NAMES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 SET SQL DIALECT . . . . . . . . . . . . . . . . . . . . . . . . . 150 SET STATISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . 151 SET TRANSACTION . . . . . . . . . . . . . . . . . . . . . . . . 152 SHOW SQL DIALECT . . . . . . . . . . . . . . . . . . . . . . . 155 SUM( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 UPDATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 UPPER( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 WHENEVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 CHAPTER 3 Procedures and Triggers Creating triggers and stored procedures . . . . . . . . . . . . 162 Nomenclature conventions . . . . . . . . . . . . . . . . . . . . 163 Assignment statement . . . . . . . . . . . . . . . . . . . . . . . 163 BEGIN … END . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 LANGUAGE REFERENCE v
Comment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 DECLARE VARIABLE . . . . . . . . . . . . . . . . . . . . . . . . 166 EXCEPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 EXECUTE PROCEDURE . . . . . . . . . . . . . . . . . . . . . . 167 EXIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 FOR SELECT…DO . . . . . . . . . . . . . . . . . . . . . . . . . 170 IF…THEN … ELSE . . . . . . . . . . . . . . . . . . . . . . . . . 171 Input parameters . . . . . . . . . . . . . . . . . . . . . . . . . 172 NEW context variables . . . . . . . . . . . . . . . . . . . . . . 173 OLD context variables . . . . . . . . . . . . . . . . . . . . . . . 174 Output parameters . . . . . . . . . . . . . . . . . . . . . . . . . 175 POST_EVENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 SELECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 SUSPEND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 WHEN … DO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 Handling exceptions . . . . . . . . . . . . . . . . . . . . . 180 Handling SQL errors . . . . . . . . . . . . . . . . . . . . . 180 Handling Firebird error codes . . . . . . . . . . . . . . 181 WHILE … DO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 CHAPTER 4 Keywords Firebird keywords . . . . . . . . . . . . . . . . . . . . . . . . 184 CHAPTER 5 User-Defined Functions A brief overview . . . . . . . . . . . . . . . . . . . . . . . . . . 189 UDF library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 abs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 acos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 ascii_char . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 ascii_val . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 asin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 atan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 atan2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 bin_and . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 vi
bin_or . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 bin_xor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 ceiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 cos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 cosh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 cot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 div . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 floor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 ln. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 log10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 lower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 ltrim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 mod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 pi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 rand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 rtrim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 sign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 sin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 sinh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 sqrt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 strlen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 substr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 tan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 tanh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 CHAPTER 6 Error Codes and Messages Error sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Error reporting and handling . . . . . . . . . . . . . . . . . . 200 Trapping errors with WHENEVER . . . . . . . . . . . . . 200 Checking SQLCODE value directly . . . . . . . . . . . . . 201 Firebird status array . . . . . . . . . . . . . . . . . . . . 201 For more information . . . . . . . . . . . . . . . . . . . . 203 SQLCODE error codes and messages . . . . . . . . . . . . . . 203 LANGUAGE REFERENCE vii
SQLCODE error messages summary . . . . . . . . . . . . 204 SQLCODE codes and messages . . . . . . . . . . . . . . . 204 Firebird status array error codes . . . . . . . . . . . . . . . . 220 CHAPTER 7 System Tables and Views Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 System tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 RDB$CHARACTER_SETS . . . . . . . . . . . . . . . . . . . . . 243 RDB$CHECK_CONSTRAINTS . . . . . . . . . . . . . . . . . . . 244 RDB$COLLATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 244 RDB$DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . . 245 RDB$DEPENDENCIES . . . . . . . . . . . . . . . . . . . . . . . 246 RDB$EXCEPTIONS . . . . . . . . . . . . . . . . . . . . . . . . 247 RDB$FIELD_DIMENSIONS . . . . . . . . . . . . . . . . . . . . 248 RDB$FIELDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 RDB$FILES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 RDB$FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 RDB$FORMATS . . . . . . . . . . . . . . . . . . . . . . . . . . 254 RDB$FUNCTION_ARGUMENTS . . . . . . . . . . . . . . . . . 255 RDB$FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . 256 RDB$GENERATORS . . . . . . . . . . . . . . . . . . . . . . . . 257 RDB$INDEX_SEGMENTS . . . . . . . . . . . . . . . . . . . . . 258 RDB$INDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 RDB$LOG_FILES . . . . . . . . . . . . . . . . . . . . . . . . . . 259 RDB$PAGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 RDB$PROCEDURE_PARAMETERS . . . . . . . . . . . . . . . . 261 RDB$PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . 262 RDB$REF_CONSTRAINTS . . . . . . . . . . . . . . . . . . . . . 263 RDB$RELATION_CONSTRAINTS . . . . . . . . . . . . . . . . . 263 RDB$RELATION_FIELDS . . . . . . . . . . . . . . . . . . . . . 264 RDB$RELATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 266 RDB$ROLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 RDB$SECURITY_CLASSES . . . . . . . . . . . . . . . . . . . . 268 RDB$TRANSACTIONS . . . . . . . . . . . . . . . . . . . . . . . 268 viii
RDB$TRIGGER_MESSAGES . . . . . . . . . . . . . . . . . . . . 269 RDB$TRIGGERS . . . . . . . . . . . . . . . . . . . . . . . . . . 269 RDB$TYPES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 RDB$USER_PRIVILEGES . . . . . . . . . . . . . . . . . . . . . 272 RDB$VIEW_RELATIONS . . . . . . . . . . . . . . . . . . . . . 273 System views . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 CHECK_CONSTRAINTS . . . . . . . . . . . . . . . . . . . . . . 275 CONSTRAINTS_COLUMN_USAGE . . . . . . . . . . . . . . . . 275 REFERENTIAL_CONSTRAINTS . . . . . . . . . . . . . . . . . . 276 TABLE_CONSTRAINTS . . . . . . . . . . . . . . . . . . . . . . 276 CHAPTER 8 Character Sets and Collation Orders Firebird character sets and collation orders . . . . . . . . . 278 Character set storage requirements . . . . . . . . . . . . 281 Additional character sets and collations . . . . . . . . . . 283 Specifying character sets . . . . . . . . . . . . . . . . . . . . . 283 Default character set for a database . . . . . . . . . . . . 284 Character set for a column in a table . . . . . . . . . . . 284 Character set for a client attachment . . . . . . . . . . . 285 Collation order for a column . . . . . . . . . . . . . . . . 285 Collation order in comparison . . . . . . . . . . . . . . . 286 Collation order in ORDER BY . . . . . . . . . . . . . . . . 286 Collation order in a GROUP BY clause . . . . . . . . . . . 286 APPENDIX A Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i LANGUAGE REFERENCE ix
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List of Tables Table 1.1 Language Reference chapters . . . . . . . . . . . . . . . . . . . . . 14 Table 2.1 SQL functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Table 2.2 Datatypes supported by Firebird . . . . . . . . . . . . . . . . . . . 19 Table 2.3 SQLCODE and message summary . . . . . . . . . . . . . . . . . . . 20 Table 2.4 Statement and function format . . . . . . . . . . . . . . . . . . . . 21 Table 2.5 The ALTER TABLE statement . . . . . . . . . . . . . . . . . . . . . . 31 Table 2.6 Compatible datatypes for CAST() . . . . . . . . . . . . . . . . . . . . . .40 Table 2.7 Procedure and trigger language extensions . . . . . . . . . . . . . 64 Table 2.8 Procedure and trigger language extensions . . . . . . . . . . . . . 84 Table 2.9 SQL privileges . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Table 2.10 SELECT statement clauses . . . . . . . . . . . . . . . . . . . . . . 144 Table 2.11 SQL Dialects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Table 2.12 SQL Dialects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 Table 3.1 SUSPEND, EXIT, and END . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Table 3.2 SUSPEND, EXIT, and END . . . . . . . . . . . . . . . . . . . . . . . . . . 178 Table 4.1 Firebird keywords . . . . . . . . . . . . . . . . . . . . . . . . . 187 Table 6.1 Status array codes that require rollback and retry . . . . . . . . . 202 Table 6.2 Where to find error-handling topics . . . . . . . . . . . . . . . . . 203 Table 6.3 SQLCODE and messages summary . . . . . . . . . . . . . . . . . 204 Table 6.4 SQLCODE codes and messages . . . . . . . . . . . . . . . . . . . 205 Table 6.5 Firebird status array error codes . . . . . . . . . . . . . . . . . . 221 Table 7.1 System tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 Table 7.2 RDB$CHARACTER_SETS . . . . . . . . . . . . . . . . . . . . . . 243 Table 7.3 RDB$CHECK_CONSTRAINTS . . . . . . . . . . . . . . . . . . . . 244 Table 7.4 RDB$COLLATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 244 Table 7.5 RDB$DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 Table 7.6 RDB$DEPENDENCIES . . . . . . . . . . . . . . . . . . . . . . . . 246 Table 7.7 RDB$EXCEPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . 247 Table 7.8 RDB$FIELD_DIMENSIONS . . . . . . . . . . . . . . . . . . . . . 248 Table 7.9 RDB$FIELDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 Table 7.10 RDB$FILES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 Table 7.11 RDB$FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 Table 7.12 RDB$FORMATS . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 LANGUAGE REFERENCE xi
LIST OF TABLES Table 7.13 RDB$FUNCTION_ARGUMENTS . . . . . . . . . . . . . . . . . . . 255 Table 7.14 RDB$FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 256 Table 7.15 RDB$GENERATORS . . . . . . . . . . . . . . . . . . . . . . . . . 257 Table 7.16 RDB$INDEX_SEGMENTS . . . . . . . . . . . . . . . . . . . . . . 258 Table 7.17 RDB$INDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 Table 7.18 RDB$PAGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 Table 7.19 RDB$PROCEDURE_PARAMETERS. . . . . . . . . . . . . . . . . . 261 Table 7.20 RDB$PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . 262 Table 7.21 RDB$REF_CONSTRAINTS . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Table 7.22 RDB$RELATION_CONSTRAINTS . . . . . . . . . . . . . . . . . . 263 Table 7.23 RDB$RELATION_FIELDS. . . . . . . . . . . . . . . . . . . . . . . 264 Table 7.24 RDB$RELATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . 266 Table 7.25 RDB$ROLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 Table 7.26 RDB$SECURITY_CLASSES . . . . . . . . . . . . . . . . . . . . . . 268 Table 7.27 RDB$TRANSACTIONS . . . . . . . . . . . . . . . . . . . . . . . . 268 Table 7.28 RDB$TRIGGER_MESSAGES . . . . . . . . . . . . . . . . . . . . . 269 Table 7.29 RDB$TRIGGERS . . . . . . . . . . . . . . . . . . . . . . . . . . . 269 Table 7.30 RDB$TYPES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Table 7.31 RDB$USER_PRIVILEGES. . . . . . . . . . . . . . . . . . . . . . . 272 Table 7.32 RDB$VIEW_RELATIONS . . . . . . . . . . . . . . . . . . . . . . . 273 Table 7.33 CHECK_CONSTRAINTS . . . . . . . . . . . . . . . . . . . . . . . 275 Table 7.34 CONSTRAINTS_COLUMN_USAGE . . . . . . . . . . . . . . . . . . 275 Table 7.35 REFERENTIAL_CONSTRAINTS . . . . . . . . . . . . . . . . . . . 276 Table 7.36 TABLE_CONSTRAINTS . . . . . . . . . . . . . . . . . . . . . . . . 276 Table 8.1 Character sets and collation orders . . . . . . . . . . . . . . . . . 278 Table 8.2 Character sets corresponding to DOS code pages . . . . . . . . . 282 Table A.1 Books in the Firebird 6 documentation set . . . . . . . . . . . . 288 Table A.2 Text conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 289 Table A.3 Syntax conventions . . . . . . . . . . . . . . . . . . . . . . . . . 290 xii
CHAPTER 1 Using the Firebird Chapter 1 Language Reference The Firebird Language Reference details the syntax and usage of SQL and Dynamic SQL (DSQL) statements for embedded applications programming and for isql-fb, the Firebird interactive SQL utility. It also describes additional language and syntax that is specific to Firebird stored procedures and triggers.
Chapter 1 Using the Firebird Language Reference Topics covered in this book The following table lists the chapters in the Language Reference, and provides a brief description of them:
Chapter Description
Chapter 1, “Using the Firebird Language Reference” Introduces the book, and describes its intended audience.
Chapter 2, “SQL Statement and Function Reference” Provides syntax and usage information for SQL and DSQL statements.
Chapter 3, “Procedures and Triggers” Describes syntax and usage information for stored procedure and trigger language.
Chapter 4, “Keywords” Lists keywords, symbols, and punctuation, that have special meaning to Firebird.
Chapter 6, “Error Codes and Messages” Summarizes Firebird error messages and error codes.
Chapter 7, “System Tables and Views” Describes Firebird system tables and views that track metadata.
Chapter 8, “Character Sets and Collation Orders” Explains all about character sets and corresponding collation orders for a variety of environments and uses.
TABLE 1.1 Language Reference chapters 14
CHAPTER 2 SQL Statement and Chapter 2 Function Reference This chapter provides the syntax and usage for each Firebird SQL statement. It includes the following topics: LANGUAGE REFERENCE 15
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Database object naming conventions When an applications programmer or end user creates a database object or refers to it by name, case is unimportant. The following limitations on naming database objects must be observed: g Start each name with an alphabetic character (A–Z or a–z). g Restrict object names to 31 characters, including dollar signs ($), underscores (_), 0 to 9, A to Z, and a to z. Some objects, such as constraint names, are restricted to 27 bytes in length. g Keep object names unique. In all cases, objects of the same type—all tables, for example—must be unique. In most cases, object names must also be unique within the database. g To use keywords, ASCII characters, case-sensitive strings, or spaces in an object name, enclose the name in double quotes. It is then a delimited identifier. Delimited identifiers must always be referenced in double quotes. For more information about naming database objects with CREATE or DECLARE statements, see the Language Reference. 16
STATEMENT LIST Statement list This chapter describes the following SQL statements: ALTER DATABASE DECLARE CURSOR EXECUTE ALTER DOMAIN DECLARE CURSOR (BLOB) EXECUTE IMMEDIATE ALTER EXCEPTION DECLARE EXTERNAL FUNCTION EXECUTE PROCEDURE ALTER INDEX DECLARE FILTER FETCH ALTER PROCEDURE DECLARE STATEMENT FETCH (BLOB) ALTER TABLE DECLARE TABLE GRANT ALTER TRIGGER DELETE INSERT BASED ON DESCRIBE INSERT CURSOR (BLOB) BEGIN DECLARE SECTION DISCONNECT OPEN CLOSE DROP DATABASE OPEN (BLOB) CLOSE (BLOB) DROP DOMAIN PREPARE COMMIT DROP EXCEPTION REVOKE CONNECT DROP EXTERNAL FUNCTION ROLLBACK CREATE DATABASE DROP FILTER SELECT CREATE DOMAIN DROP INDEX SET DATABASE CREATE EXCEPTION DROP PROCEDURE SET GENERATOR CREATE GENERATOR DROP ROLE SET NAMES CREATE INDEX DROP SHADOW SET SQL DIALECT CREATE PROCEDURE DROP TABLE SET STATISTICS CREATE ROLE DROP TRIGGER SET TRANSACTION CREATE SHADOW DROP VIEW SHOW SQL DIALECT CREATE TABLE END DECLARE SECTION UPDATE CREATE TRIGGER EVENT INIT WHENEVER CREATE VIEW EVENT WAIT LANGUAGE REFERENCE 17
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Function list The following table lists the SQL functions described in this chapter: Function Type Purpose AVG() Aggregate Calculates the average of a set of values CAST() Conversion Converts a column from one datatype to another COUNT() Aggregate Returns the number of rows that satisfy a query’s search condition GEN_ID() Numeric Returns a system-generated value MAX() Aggregate Retrieves the maximum value from a set of values MIN() Aggregate Retrieves the minimum value from a set of values SUM() Aggregate Totals the values in a set of numeric values UPPER() Conversion Converts a string to all uppercase TABLE 2.1 SQL functions Aggregate functions perform calculations over a series of values, such as the columns retrieved with a SELECT statement. Conversion functions transform datatypes, either converting them from one type to another, or by converting CHARACTER datatypes to all uppercase. The numeric function, GEN_ID(), produces a system-generated number that can be inserted into a column requiring a numeric datatype. 18
DATATYPES Datatypes Firebird supports most SQL datatypes, a dynamically sizable datatype called a Blob, and arrays of datatypes. It does not support arrays of Blobs. The following table lists the datatypes available to SQL statements in Firebird: Name Size Range/Precision Description BLOB Variable • None • Dynamically sizable dataype for • Blob segment size is limited to 64K storing large data such as graphics, text, and digitized voice • Basic structural unit is the segment• Blob subtype describes Blob contents CHAR(n) n characters • 1 to 32,767 bytes • Fixed length CHAR or text string type • Character set character size determines • Alternate keyword: CHARACTER the maximum number of characters that can fit in 32K DATE 64 bits 1 Jan 100 a.d. to 29 Feb 32768 a.d. ISC_DATE DECIMAL (precision, scale) Variable • precision = 1 to 18; specifies at least • Number with a decimal point scale (16, 32, or precision digits of precision to store digits from the right 64 bits) • scale = 1 to 18; specifies number of • Example: DECIMAL(10, 3) holds decimal places for storage numbers accurately in the following • Must be less than or equal to precision format: ppppppp.sss DOUBLE PRECISION 64 bitsa 2.225 x 10–308 to 1.797 x 10308 IEEE double precision: 15 digits FLOAT 32 bits 1.175 x 10–38 to 3.402 x 1038 IEEE single precision: 7 digits INTEGER 32 bits –2,147,483,648 to 2,147,483,647 Signed long (longword) NUMERIC (precision, scale) Variable • precision = 1 to 18; specifies exactly • Number with a decimal point scale (16, 32, or precision digits of precision to store digits from the right 64 bits) • scale = 1 to 18; specifies number of • Example: NUMERIC(10,3) holds decimal places for storage numbers accurately in the following • Must be less than or equal to precision format: ppppppp.sss SMALLINT 16 bits –32,768 to 32,767 Signed short (word) TABLE 2.2 Datatypes supported by Firebird LANGUAGE REFERENCE 19
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Name Size Range/Precision Description TIME 64 bits 0:00 AM to 23:59.9999 PM ISC_TIME TIMESTAMP 64 bits 1 Jan 100 a.d. to 29 Feb 32768 a.d. Also includes time information VARCHAR (n) n characters • 1 to 32,765 bytes • Variable length CHAR or text string • Character set character size determines type the maximum number of characters • Alternate keywords: CHAR VARYING, that can fit in 32K CHARACTER VARYING TABLE 2.2 Datatypes supported by Firebird (continued) a. Actual size of DOUBLE is platform-dependent. Most platforms support the 64-bit size. Error handling Every time an executable SQL statement is executed, the SQLCODE variable is set to indicate its success or failure. No SQLCODE is generated for declarative statements that are not executed, such as DECLARE CURSOR, DECLARE TABLE, and DECLARE STATEMENT. The following table lists values that are returned to SQLCODE: SQLCODE Message Meaning < 0 SQLERROR Error occurred; statement did not execute 0 SUCCESS Successful execution +1–99 SQLWARNING System warning or informational message +100 NOT FOUND No qualifying rows found, or end of current active set of rows reached TABLE 2.3 SQLCODE and message summary When an error occurs in isql, Firebird displays an error message. In embedded applications, the programmer must provide error handling by checking the value of SQLCODE. To check SQLCODE, use one or a combination of the following approaches: g Test for SQLCODE values with the WHENEVER statement. g Check SQLCODE directly. 20
USING STATEMENT AND FUNCTION DEFINITIONS g Use the isc_print_sqlerror( ) routine to display specific error messages. For more information about error handling, see the Embedded SQL Guide. Using statement and function definitions Each statement and function definition includes the following elements: Element Description Title Statement name Definition The statement’s main purpose and availability Syntax Diagram of the statement and its parameters Argument Parameters available for use with the statement Description Information about using the statement Examples Examples of using the statement in a program and in isql See also Where to find more information about the statement or others related to it TABLE 2.4 Statement and function format Most statements can be used in SQL, DSQL, and isql. In many cases, the syntax is nearly identical, except that embedded SQL statements must always be preceded by the EXEC SQL keywords. EXEC SQL is omitted from syntax statements for clarity. In other cases there are small, but significant differences among SQL, DSQL, and isql syntax. In these cases, separate syntax statements appear under the statement heading. LANGUAGE REFERENCE 21
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE ALTER DATABASE Adds secondary files to the current database. Available in SQL, DSQL, and isql. Syntax ALTER {DATABASE | SCHEMA} ADD <add_clause>; <add_clause> = FILE ’filespec’ [<fileinfo>] [<add_clause>] <fileinfo> = LENGTH [=] int [PAGE[S]] | STARTING [AT [PAGE]] int [<fileinfo>] IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description SCHEMA Alternative keyword for DATABASE ADD FILE ‘filespec’ Adds one or more secondary files to receive database pages after the primary file is filled; for a remote database, associate secondary files with the same node LENGTH [=] int [PAGE[S]] Specifies the range of pages for a secondary file by providing the number of pages in each file STARTING [AT [PAGE]] int Specifies a range of pages for a secondary file by providing the starting page number Description ALTER DATABASE adds secondary files to an existing database. Secondary files permit databases to spread across storage devices, but they must remain on the same node as the primary database file. A database can be altered by its creator, the SYSDBA user, and any users with operating system root privileges. ALTER DATABASE requires exclusive access to the database. Note Firebird dynamically expands the last file in a database as needed until it reaches the 4GB limit. You should be aware that specifying a LENGTH for such files has no effect. You cannot use ALTER DATABASE to split an existing database file. For example, if your existing database is 80,000 pages long and you add a secondary file STARTING AT 50000, Firebird starts the new database file at page 80,001. 22
ALTER DOMAIN Tip To split an existing database file into smaller files, back it up and restore it. When you restore a database, you are free to specify secondary file sizes at will, without reference to the number and size of the original files. Example The following isql statement adds two secondary files to an existing database. The command creates a secondary database file called employee2.fdb that is 10,000 pages long and another called employee3.fdb. interBase starts using employee2.fdb only when the primary file reaches 10,000 pages. ALTER DATABASE ADD FILE ’employee2.fdb’ STARTING AT PAGE 10001 LENGTH 10000 ADD FILE ’employee3.fdb’; See Also CREATE DATABASE, DROP DATABASE See the Data Definition Guide for more information about multi-file databases and the Operations Guide for more information about exclusive database access. ALTER DOMAIN Changes a domain definition. Available in SQL, DSQL, and isql. ALTER DOMAIN name { SET DEFAULT {literal | NULL | USER} | DROP DEFAULT | ADD [CONSTRAINT] CHECK (<dom_search_condition>) | DROP CONSTRAINT | new_col_name | TYPE datatype}; <dom_search_condition> = { VALUE <operator> <val> | VALUE [NOT] BETWEEN <val> AND <val> | VALUE [NOT] LIKE <val> [ESCAPE <val>] | VALUE [NOT] IN (<val> [, <val> …]) | VALUE IS [NOT] NULL | VALUE [NOT] CONTAINING <val> | VALUE [NOT] STARTING [WITH] <val> LANGUAGE REFERENCE 23
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE | (<dom_search_condition>) | NOT <dom_search_condition> | <dom_search_condition> OR <dom_search_condition> | <dom_search_condition> AND <dom_search_condition> } <operator> = {= | < | > | <= | >= | !< | !> | <> | !=} IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing domain SET DEFAULT Specifies a default column value that is entered when no other entry is made. Values: • literal—Inserts a specified string, numeric value, or date value• NULL—Enters a NULL value• USER—Enters the user name of the current user; column must be of compatible text type to use the default • Defaults set at column level override defaults set at the domain level DROP DEFAULT Drops an existing default ADD [CONSTRAINT] CHECK Adds a CHECK constraint to the domain definition; a domain dom_search_condition definition can include only one CHECK constraint DROP CONSTRAINT Drops CHECK constraint from the domain definition new_col_name Changes the domain name TYPE data_type Changes the domain datatype Description ALTER DOMAIN changes any aspect of an existing domain except its NOT NULL setting. Changes made to a domain definition affect all column definitions based on the domain that have not been overridden at the table level. Note To change a datatype or NOT NULL setting of a domain, drop the domain and recreate it with the desired combination of features. A domain can be altered by its creator, the SYSDBA user, and any users with operating system root privileges. 24
ALTER EXCEPTION Example The following isql statements create a domain that must have a value > 1,000, then alter it by setting a default of 9,999: CREATE DOMAIN CUSTNO AS INTEGER CHECK (VALUE > 1000); ALTER DOMAIN CUSTNO SET DEFAULT 9999; See Also CREATE DOMAIN, CREATE TABLE, DROP DOMAIN For a complete discussion of creating domains, and using them to create column definitions, see the Data Definition Guide. ALTER EXCEPTION Changes the message associated with an existing exception. Available in DSQL and isql. Syntax ALTER EXCEPTION name ’message’ Argument Description name Name of an existing exception message ‘message’ Quoted string containing ASCII values Description ALTER EXCEPTION changes the text of an exception error message. An exception can be altered by its creator, the SYSDBA user, and any users with operating system root privileges. Example This isql statement alters the message of an exception: ALTER EXCEPTION CUSTOMER_CHECK ’Hold shipment for customer remittance.’; See Also ALTER PROCEDURE, ALTER TRIGGER, CREATE EXCEPTION, CREATE PROCEDURE, CREATE TRIGGER, DROP EXCEPTION For more information on creating, raising, and handling exceptions, see the Data Definition Guide. LANGUAGE REFERENCE 25
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE ALTER INDEX Activates or deactivates an index. Available in SQL, DSQL, and isql. Syntax ALTER INDEX name {ACTIVE | INACTIVE}; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing index ACTIVE Changes an INACTIVE index to an ACTIVE one INACTIVE Changes an ACTIVE index to an INACTIVE one Description ALTER INDEX makes an inactive index available for use, or disables the use of an active index. Deactivating and reactivating an index is useful when changes in the distribution of indexed data cause the index to become unbalanced. Before inserting or updating a large number of rows, deactivate a table’s indexes to avoid altering the index incrementally. When finished, reactivate the index. Reactivating a deactivated index rebuilds and rebalances an index. If an index is in use, ALTER INDEX does not take effect until the index is no longer in use. ALTER INDEX fails and returns an error if the index is defined for a UNIQUE, PRIMARY KEY, or FOREIGN KEY constraint. To alter such an index, use DROP INDEX to delete the index, then recreate it with CREATE INDEX. An index can be altered by its creator, the SYSDBA user, and any users with operating system root privileges. Note To add or drop index columns or keys, use DROP INDEX to delete the index, then recreate it with CREATE INDEX. Example The following isql statements deactivate and reactivate an index to rebuild it: ALTER INDEX BUDGETX INACTIVE; ALTER INDEX BUDGETX ACTIVE; See Also ALTER TABLE, CREATE INDEX, DROP INDEX, SET STATISTICS 26
ALTER PROCEDURE ALTER PROCEDURE Changes the definition of an existing stored procedure. Available in DSQL and isql. Syntax ALTER PROCEDURE name [(param <datatype> [, param <datatype> …])] [RETURNS (param <datatype> [, param <datatype> …])] AS <procedure_body> [terminator] Argument Description name Name of an existing procedure param datatype Input parameters used by the procedure; legal datatypes are listed under CREATE PROCEDURE RETURNS param datatype Output parameters used by the procedure; legal datatypes are listed under CREATE PROCEDURE procedure_body The procedure body includes: • Local variable declarations• A block of statements in procedure and trigger languageSee CREATE PROCEDURE for a complete description terminator Terminator defined by the isql SET TERM command to signify the end of the procedure body; required by isql Description ALTER PROCEDURE changes an existing stored procedure without affecting its dependencies. It can modify a procedure’s input parameters, output parameters, and body. The complete procedure header and body must be included in the ALTER PROCEDURE statement. The syntax is exactly the same as CREATE PROCEDURE, except CREATE is replaced by ALTER. IMPORTANT Be careful about changing the type, number, and order of input and output parameters to a procedure, since existing application code may assume the procedure has its original format. A procedure can be altered by its creator, the SYSDBA user, and any users with operating system root privileges. Procedures in use are not altered until they are no longer in use. ALTER PROCEDURE changes take effect when they are committed. Changes are then reflected in all applications that use the procedure without recompiling or relinking. LANGUAGE REFERENCE 27
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Example The following isql statements alter the GET_EMP_PROJ procedure, changing the return parameter to have a datatype of VARCHAR(20): SET TERM !! ; ALTER PROCEDURE GET_EMP_PROJ (EMP_NO SMALLINT) RETURNS (PROJ_ID VARCHAR(20)) AS BEGIN FOR SELECT PROJ_ID FROM EMPLOYEE_PROJECT WHERE EMP_NO = :emp_no INTO :proj_id DO SUSPEND; END !! SET TERM ; !! See Also CREATE PROCEDURE, DROP PROCEDURE, EXECUTE PROCEDURE For more information on creating and using procedures, see the Data Definition Guide. For a complete description of the statements in procedure and trigger language, see Chapter 3, “Procedures and Triggers.” ALTER TABLE Changes a table by adding, dropping, or modifying columns or integrity constraints. Available in SQL, DSQL, and isql. Syntax ALTER TABLE table <operation> [, <operation> …]; <operation> = {ADD <col_def> | ADD <tconstraint> | ALTER [COLUMN] column_name <alt_col_clause> | DROP col | DROP CONSTRAINT constraint} <alt_col_clause> = {TO new_col_name | TYPE new_col_datatype | POSITION new_col_position} 28
ALTER TABLE <col_def> = col {<datatype> | COMPUTED [BY] (<expr>) | domain} [DEFAULT {literal | NULL | USER}] [NOT NULL] [<col_constraint>] [COLLATE collation] <datatype> = {SMALLINT | INTEGER | FLOAT | DOUBLE PRECISION}[<array_dim>] | (DATE | TIME | TIMESTAMP}[<array_dim>] | {DECIMAL | NUMERIC} [(precision [, scale])] [<array_dim>] | {CHAR | CHARACTER | CHARACTER VARYING | VARCHAR} [(int)] [<array_dim>] [CHARACTER SET charname] | {NCHAR | NATIONAL CHARACTER | NATIONAL CHAR} [VARYING] [(int)] [<array_dim>] | BLOB [SUB_TYPE {int | subtype_name}] [SEGMENT SIZE int] [CHARACTER SET charname] | BLOB [(seglen [, subtype])]<array_dim> = [[x:]y [, [x:]y …]] <expr> = A valid SQL expression that results in a single value. <col_constraint> = [CONSTRAINT constraint] { UNIQUE | PRIMARY KEY | REFERENCES other_table [(other_col [, other_col …])] [ON DELETE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] [ON UPDATE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] | CHECK (<search_condition>)} <tconstraint> = [CONSTRAINT constraint] {{PRIMARY KEY | UNIQUE} (col [, col …]) | FOREIGN KEY (col [, col …]) REFERENCES other_table [ON DELETE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] [ON UPDATE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] | CHECK (<search_condition>)} LANGUAGE REFERENCE 29
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE <search_condition> = <val> <operator> {<val> | (<select_one>)} | <val> [NOT] BETWEEN <val> AND <val> | <val> [NOT] LIKE <val> [ESCAPE <val>] | <val> [NOT] IN (<val> [, <val> …] | <select_list>) | <val> IS [NOT] NULL | <val> {>= | <=} | <val> [NOT] {= | < | >} | {ALL | SOME | ANY} (<select_list>) | EXISTS (<select_expr>) | SINGULAR (<select_expr>) | <val> [NOT] CONTAINING <val> | <val> [NOT] STARTING [WITH] <val> | (<search_condition>) | NOT <search_condition> | <search_condition> OR <search_condition> | <search_condition> AND <search_condition> <val> = { col [<array_dim>] | :variable | <constant> | <expr> | <function> | udf ([<val> [, <val> …]]) | NULL | USER | RDB$DB_KEY | ? } [COLLATE collation] <constant> = num | 'string' | charsetname 'string' <function> = COUNT (* | [ALL] <val> | DISTINCT <val>) | SUM ([ALL] <val> | DISTINCT <val>) | AVG ([ALL] <val> | DISTINCT <val>) | MAX ([ALL] <val> | DISTINCT <val>) | MIN ([ALL] <val> | DISTINCT <val>) | CAST (<val> AS <datatype>) | UPPER (<val>) | GEN_ID (generator, <val>) <operator> = {= | < | > | <= | >= | !< | !> | <> | !=} <select_one> = SELECT on a single column; returns exactly one value. <select_list> = SELECT on a single column; returns zero or more values. <select_expr> = SELECT on a list of values; returns zero or more values. 30
ALTER TABLE IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Notes on ALTER TABLE syntax g The column constraints for referential integrity were new in Firebird 5. See constraint_def in Table 2.5 and the Description for ALTER TABLE on page 33. g You cannot specify a COLLATE clause for Blob columns. g When declaring arrays, you must include the outermost brackets, shown below in bold. For example, the following statement creates a 5 by 5 two-dimensional array of strings, each of which is 6 characters long: my_array = varchar(6)[5,5] Use the colon (:) to specify an array with a starting point other than 1. The following example creates an array of integers that begins at 20 and ends at 30: my_array = integer[20:30] g For the full syntax of search_condition, see CREATE TABLE. Argument Description table Name of an existing table to modify operation Action to perform on the table. Valid options are: • ADD a new column or table constraint to a table• DROP an existing column or constraint from a table col_def Description of a new column to add • Must include a column name and datatype• Can also include default values, column constraints, and a specific collation order col Name of the column to add or drop; column name must be unique within the table datatype Datatype of the column; see “Datatypes” on page 19. ALTER [COLUMN] Modifies column names, datatypes, and positions. TABLE 2.5 The ALTER TABLE statement LANGUAGE REFERENCE 31
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description COMPUTED [BY] expr Specifies that the value of the column’s data is calculated from expr at runtime and is therefore not allocated storage space in the database • expr can be any arithmetic expression valid for the datatypes in the expression • Any columns referenced in expr must exist before they can be used in expr • expr cannot reference Blob columns• expr must return a single value, and cannot return an array domain Name of an existing domain DEFAULT Specifies a default value for column data; this value is entered when no other entry is made; possible values are: • literal: Inserts a specified string, numeric value, or date value• NULL: Enters a NULL value• USER: Enters the user name of the current user; column must be of compatible text type to use the default Defaults set at column level override defaults set at the domain level CONSTRAINT constraint Name of a column or table constraint; the constraint name must be unique within the table constraint_def Specifies the kind of column constraint; valid options are UNIQUE, PRIMARY KEY, CHECK, and REFERENCES CHECK search_condition An attempt to enter a new value in the column fails if the value does not meet the search_condition REFERENCES Specifies that the column values are derived from column values in another table; if you do not specify column names, Firebird looks for a column with the same name as the referencing column in the referenced table TABLE 2.5 The ALTER TABLE statement 32
ALTER TABLE Argument Description ON DELETE | ON UPDATE Used with REFERENCES: Changes a foreign key whenever the referenced primary key changes; valid options are: • [Default] NO ACTION: Does not change the foreign key; may cause the primary key update to fail due to referential integrity checks • CASCADE: For ON DELETE, deletes the corresponding foreign key; for ON UPDATE, updates the corresponding foreign key to the new value of the primary key • SET NULL: Sets all the columns of the corresponding foreign key to NULL• SET DEFAULT: Sets every column of the corresponding foreign key is set to its default value in effect when the referential integrity constraint is defined; when the default for a foreign column changes after the referential integrity constraint is defined, the change does not have an effect on the default value used in the referential integrity constraint NOT NULL Specifies that a column cannot contain a NULL value • If a table already has rows, a new column cannot be NOT NULL• NOT NULL is a column attribute only DROP CONSTRAINT Drops the specified table constraint table_constraint Description of the new table constraint; constraints can be PRIMARY KEY, UNIQUE, FOREIGN KEY, or CHECK COLLATE collation Establishes a default sorting behavior for the column; see Chapter 8, “Character Sets and Collation Orders” for more information TABLE 2.5 The ALTER TABLE statement Description ALTER TABLE modifies the structure of an existing table. A single ALTER TABLE statement can perform multiple adds and drops. g A table can be altered by its creator, the SYSDBA user, and any users with operating system superuser privileges. g ALTER TABLE fails if the new data in a table violates a PRIMARY KEY or UNIQUE constraint definition added to the table. Dropping a column fails if any of the following are true: · The column is part of a UNIQUE, PRIMARY, or FOREIGN KEY constraint · The column is used in a CHECK constraint · The column is used in the value expression of a computed column · The column is referenced by another database object such as a view LANGUAGE REFERENCE 33
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE IMPORTANT When a column is dropped, all data stored in it is lost. Referential integrity constraints g To ensure that the referential integrity of foreign keys is preserved, use the ON UPDATE and ON DELETE options for all REFERENCES statements. The values for these cascading referential integrity options are given in Table 2.5, “The ALTER TABLE statement,” on page 31. g If you do not use the ON UPDATE and ON DELETE options, you must drop the constraint or computed column before dropping the table column. To drop a PRIMARY KEY or UNIQUE constraints that is referenced by FOREIGN KEY constraints, drop the FOREIGN KEY constraint before dropping the PRIMARY KEY or UNIQUE key it references. g You can create a FOREIGN KEY reference to a table that is owned by someone else only if that owner has explicitly granted you the REFERENCES privilege on that table using GRANT. Any user who updates your foreign key table must have REFERENCES or SELECT privileges on the referenced primary key table. g You can add a check constraint to a column that is based on a domain, but be aware that changes to tables that contain CHECK constraints with subqueries may cause constraint violations. g Naming column constraints is optional. If you do not specify a name, Firebird assigns a system-generated name. Assigning a descriptive name can make a constraint easier to find for changing or dropping, and easier to find when its name appears in a constraint violation error message. Example The following isql statement adds a column to a table and drops a column: ALTER TABLE COUNTRY ADD CAPITAL VARCHAR(25), DROP CURRENCY; This statement results in the loss of all data in the dropped CURRENCY column. The next isql statement adds two columns to a table and defines a UNIQUE constraint on one of them: ALTER TABLE COUNTRY ADD CAPITAL VARCHAR(25) NOT NULL UNIQUE, ADD LARGEST_CITY VARCHAR(25) NOT NULL; The next isql statement changes the name of the LARGEST_CITY column to BIGGEST_CITY: ALTER TABLE COUNTRY ALTER LARGEST_CITY TO BIGGEST_CITY; See Also ALTER DOMAIN, CREATE DOMAIN, CREATE TABLE For more information about altering tables, see the Embedded SQL Guide. 34
ALTER TRIGGER ALTER TRIGGER Changes an existing trigger. Available in DSQL and isql. Syntax ALTER TRIGGER name [ACTIVE | INACTIVE] [{BEFORE | AFTER} {DELETE | INSERT | UPDATE}] [POSITION number] [AS <trigger_body>] [terminator] Argument Description name Name of an existing trigger ACTIVE [Default] Specifies that a trigger action takes effect when fired INACTIVE Specifies that a trigger action does not take effect BEFORE Specifies the trigger fires before the associated operation takes place AFTER Specifies the trigger fires after the associated operation takes place DELETE|INSERT Specifies the table operation that causes the trigger to fire |UPDATE POSITION number Specifies order of firing for triggers before the same action or after the same action • number must be an integer between 0 and 32,767, inclusive• Lower-number triggers fire first• Triggers for a table need not be consecutive; triggers on the same action with the same position number fire in random order trigger_body Body of the trigger: a block of statements in procedure and trigger language • See CREATE TRIGGER for a complete description terminator Terminator defined by the isql SET TERM command to signify the end of the trigger body; not needed when altering only the trigger header Description ALTER TRIGGER changes the definition of an existing trigger. If any of the arguments to ALTER TRIGGER are omitted, then they default to their current values, that is the value specified by CREATE TRIGGER, or the last ALTER TRIGGER. ALTER TRIGGER can change: LANGUAGE REFERENCE 35
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE g Header information only, including the trigger activation status, when it performs its actions, the event that fires the trigger, and the order in which the trigger fires compared to other triggers. g Body information only, the trigger statements that follow the AS clause. g Header and trigger body information. In this case, the new trigger definition replaces the old trigger definition. A trigger can be altered by its creator, the SYSDBA user, and any users with operating system root privileges. Note To alter a trigger defined automatically by a CHECK constraint on a table, use ALTER TABLE to change the constraint definition. Examples The following isql statement modifies the trigger, SET_CUST_NO, to be inactive: ALTER TRIGGER SET_CUST_NO INACTIVE; The next isql statement modifies the trigger, SET_CUST_NO, to insert a row into the table, NEW_CUSTOMERS, for each new customer. SET TERM !! ; ALTER TRIGGER SET_CUST_NO FOR CUSTOMER BEFORE INSERT AS BEGIN NEW.CUST_NO = GEN_ID(CUST_NO_GEN, 1); INSERT INTO NEW_CUSTOMERS(NEW.CUST_NO, TODAY) END !! SET TERM ; !! See Also CREATE TRIGGER, DROP TRIGGER For a complete description of the statements in procedure and trigger language, see Chapter 3, “Procedures and Triggers.” For more information about triggers, see the Data Definition Guide. AVG( ) Calculates the average of numeric values in a specified column or expression. Available in SQL, DSQL, and isql. 36
AVG( ) Syntax AVG ([ALL] value | DISTINCT value) Argument Description ALL Returns the average of all values DISTINCT Eliminates duplicate values before calculating the average value A column or expression that evaluates to a numeric datatype Description AVG() is an aggregate function that returns the average of the values in a specified column or expression. Only numeric datatypes are allowed as input to AVG(). If a field value involved in a calculation is NULL or unknown, it is automatically excluded from the calculation. Automatic exclusion prevents averages from being skewed by meaningless data. AVG() computes its value over a range of selected rows. If the number of rows returned by a SELECT is zero, AVG() returns a NULL value. Examples The following embedded SQL statement returns the average of all rows in a table: EXEC SQL SELECT AVG (BUDGET) FROM DEPARTMENT INTO :avg_budget; The next embedded SQL statement demonstrates the use of SUM(), AVG(), MIN(), and MAX() over a subset of rows in a table: EXEC SQL SELECT SUM (BUDGET), AVG (BUDGET), MIN (BUDGET), MAX (BUDGET) FROM DEPARTMENT WHERE HEAD_DEPT = :head_dept INTO :tot_budget, :avg_budget, :min_budget, :max_budget; See Also COUNT( ), MAX( ), MIN( ), SUM( ) LANGUAGE REFERENCE 37
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE BASED ON Declares a host-language variable based on a column. Available in SQL. Syntax BASED [ON] [dbhandle.]table.col[.SEGMENT] variable; Argument Description dbhandle Handle for the database in which a table resides in a multi-database program; dbhandle must be previously declared in a SET DATABASE statement table.col Name of table and name of column on which the variable is based .SEGMENT Bases the local variable size on the segment length of the Blob column during BLOB FETCH operations; use only when table.col refers to a column of BLOB datatype variable Name of the host-language variable that inherits the characteristics of a database column Description BASED ON is a preprocessor directive that creates a host-language variable based on a column definition. The host variable inherits the attributes described for the column and any characteristics that make the variable type consistent with the programming language in use. For example, in C, BASED ON adds one byte to CHAR and VARCHAR variables to accommodate the NULL character terminator. Use BASED ON in a program’s variable declaration section. Note BASED ON does not require the EXEC SQL keywords. To declare a host-language variable large enough to hold a Blob segment during FETCH operations, use the SEGMENT option of the BASED ON clause. The variable’s size is derived from the segment length of a Blob column. If the segment length for the Blob column is changed in the database, recompile the program to adjust the size of host variables created with BASED ON. Examples The following embedded statements declare a host variable based on a column: EXEC SQL BEGIN DECLARE SECTION BASED_ON EMPLOYEE.SALARY salary; EXEC SQL END DECLARE SECTION; See Also BEGIN DECLARE SECTION, CREATE TABLE, END DECLARE SECTION 38
BEGIN DECLARE SECTION BEGIN DECLARE SECTION Identifies the start of a host-language variable declaration section. Available in SQL. Syntax BEGIN DECLARE SECTION; Description BEGIN DECLARE SECTION is used in embedded SQL applications to identify the start of host-language variable declarations for variables that will be used in subsequent SQL statements. BEGIN DECLARE SECTION is also a preprocessor directive that instructs gpre to declare SQLCODE automatically for the applications programmer. IMPORTANT BEGIN DECLARE SECTION must always appear within a module’s global variable declaration section. Example The following embedded SQL statements declare a section and a host-language variable: EXEC SQL BEGIN DECLARE SECTION; BASED ON EMPLOYEE.SALARY salary; EXEC SQL END DECLARE SECTION; See Also BASED ON, END DECLARE SECTION CAST( ) Converts a column from one datatype to another. Available in SQL, DSQL, and isql. Syntax CAST (value AS datatype) Argument Description val A column, constant, or expression; in SQL, val can also be a host-language variable, function, or UDF datatype Datatype to which to convert Description CAST() allows mixing of numerics and characters in a single expression by converting val to a specified datatype. Normally, only similar datatypes can be compared in search conditions. CAST() can be used in search conditions to translate one datatype into another for comparison purposes. LANGUAGE REFERENCE 39
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Datatypes can be converted as shown in the following table: From datatype class To datatype class Numeric character, varying character, date, time, timestamp Character, varying character numeric, date, time, timestamp Date character, varying character, timestamp Time character, varying character, timestamp Timestamp character, varying character, date, time Blob, arrays — TABLE 2.6 Compatible datatypes for CAST() An error results if a given datatype cannot be converted into the datatype specified in CAST(). Example In the following WHERE clause, CAST() is used to translate a CHARACTER datatype, INTERVIEW_DATE, to a DATE datatype to compare against a DATE datatype, HIRE_DATE: . . . WHERE HIRE_DATE = CAST (INTERVIEW_DATE AS DATE); See Also UPPER( ) CLOSE Closes an open cursor. Available in SQL. Syntax CLOSE cursor; Argument Description cursor Name of an open cursor Description CLOSE terminates the specified cursor, releasing the rows in its active set and any associated system resources. A cursor is a one-way pointer into the ordered set of rows retrieved by the select expression in the DECLARE CURSOR statement. A cursor enables sequential access to retrieved rows in turn and update in place. 40
CLOSE (BLOB) There are four related cursor statements: Stage Statement Purpose 1 DECLARE CURSOR Declares the cursor; the SELECT statement determines rows retrieved for the cursor 2 OPEN Retrieves the rows specified for retrieval with DECLARE CURSOR; the resulting rows become the cursor’s active set 3 FETCH Retrieves the current row from the active set, starting with the first row; subsequent FETCH statements advance the cursor through the set 4 CLOSE Closes the cursor and releases system resources FETCH statements cannot be issued against a closed cursor. Until a cursor is closed and reopened, Firebird does not reevaluate values passed to the search conditions. Another user can commit changes to the database while a cursor is open, making the active set different the next time that cursor is reopened. Note In addition to CLOSE, COMMIT and ROLLBACK automatically close all cursors in a transaction. Example The following embedded SQL statement closes a cursor: EXEC SQL CLOSE BC; See Also CLOSE (BLOB), COMMIT, DECLARE CURSOR, FETCH, OPEN, ROLLBACK CLOSE (BLOB) Terminates a specified Blob cursor and releases associated system resources. Available in SQL. Syntax CLOSE blob_cursor; Argument Description blob_cursor Name of an open Blob cursor Description CLOSE closes an opened read or insert Blob cursor. Generally a Blob cursor should only be closed after: g Fetching all the Blob segments for BLOB READ operations. LANGUAGE REFERENCE 41
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE g Inserting all the segments for BLOB INSERT operations. Example The following embedded SQL statement closes a Blob cursor: EXEC SQL CLOSE BC; See Also DECLARE CURSOR (BLOB), FETCH (BLOB), INSERT CURSOR (BLOB), OPEN (BLOB) COMMIT Makes a transaction’s changes to the database permanent, and ends the transaction. Available in SQL, DSQL, and isql. Syntax COMMIT [WORK] [TRANSACTION name] [RELEASE] [RETAIN [SNAPSHOT]]; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description WORK An optional word used for compatibility with other relational databases that require it TRANSACTION name Commits transaction name to database. Without this option, COMMIT affects the default transaction RELEASE Available for compatibility with earlier versions of Firebird RETAIN [SNAPSHOT] Commits changes and retains current transaction context Description COMMIT is used to end a transaction and: g Write all updates to the database. g Make the transaction’s changes visible to subsequent SNAPSHOT transactions or READ COMMITTED transactions. g Close open cursors, unless the RETAIN argument is used. A transaction ending with COMMIT is considered a successful termination. Always use COMMIT or ROLLBACK to end the default transaction. 42
COMMIT Tip After read-only transactions, which make no database changes, use COMMIT rather than ROLLBACK. The effect is the same, but the performance of subsequent transactions is better and the system resources used by them are reduced. IMPORTANT The RELEASE argument is only available for compatibility with previous versions of Firebird. To detach from a database use DISCONNECT. Examples The following isql statement makes permanent the changes to the database made by the default transaction: COMMIT; The next embedded SQL statement commits a named transaction: EXEC SQL COMMIT TR1; The following embedded SQL statement uses COMMIT RETAIN to commit changes while maintaining the current transaction context: EXEC SQL COMMIT RETAIN; See Also DISCONNECT, ROLLBACK For more information about handling transactions, see the Embedded SQL Guide. LANGUAGE REFERENCE 43
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE CONNECT Attaches to one or more databases. Available in SQL. A subset of CONNECT options is available in isql. Syntax isql form: CONNECT ’filespec’ [USER ’username’][PASSWORD ’password’] [CACHE int] [ROLE ’rolename’] SQL form: CONNECT [TO] {ALL | DEFAULT} <config_opts> | <db_specs> <config_opts> [, <db_specs> <config_opts>...]; <db_specs> = dbhandle | {’filespec’ | :variable} AS dbhandle <config_opts> = [USER {’username’ | :variable}] [PASSWORD {’password’ | :variable}] [ROLE {’rolename’ | :variable}] [CACHE int [BUFFERS]] Argument Description {ALL | DEFAULT} Connects to all databases specified with SET DATABASE; options specified with CONNECT TO ALL affect all databases. ’filespec’ Database file name; can include path specification and node. The filespec must be in quotes if it includes spaces. dbhandle Database handle declared in a previous SET DATABASE statement; available in embedded SQL but not in isql. :variable Host-language variable specifying a database, user name, or password; available in embedded SQL but not in isql. AS dbhandle Attaches to a database and assigns a previously declared handle to it; available in embedded SQL but not in isql. USER {’username’ | :variable} String or host-language variable that specifies a user name for use when attaching to the database. The server checks the user name against the security database. User names are case insensitive on the server. 44
CONNECT Argument Description PASSWORD {‘password’ | :variable} String or host-language variable, up to 8 characters in size, that specifies password for use when attaching to the database. The server checks the user name and password against the security database. Case sensitivity is retained for the comparison. ROLE {‘rolename’ | :variable} String or host-language variable, up to 31 characters in size, which specifies the role that the user adopts on connection to the database. The user must have previously been granted membership in the role to gain the privileges of that role. Regardless of role memberships granted, the user has the privileges of a role at connect time only if a ROLE clause is specified in the connection. The user can adopt at most one role per connection, and cannot switch roles except by reconnecting. CACHE int [BUFFERS] Sets the number of cache buffers for a database, which determines the number of database pages a program can use at the same time. Values for int: • Default: 256 • Maximum value: system-dependentDo not use the filespec form of database name with cache assignments. Description The CONNECT statement: g Initializes database data structures. g Determines if the database is on the originating node (a local database) or on another node (a remote database). An error message occurs if Firebird cannot locate the database. g Optionally specifies one or more of a user name, password, or role for use when attaching to the database. PC clients must always send a valid user name and password. Firebird recognizes only the first 8 characters of a password. If an Firebird user has ISC_USER and ISC_PASSWORD environment variables set and the user defined by those variables is not in the security.fdb, the user will receive the following error when attempting to view security.fdb users from the local server manager connection: “undefined user name and password.” This applies only to the local connection; the automatic connection made through Server Manager bypasses user security. LANGUAGE REFERENCE 45
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE g Attaches to the database and verifies the header page. The database file must contain a valid database, and the on-disk structure (ODS) version number of the database must be the one recognized by the installed version of Firebird on the server, or Firebird returns an error. g Optionally establishes a database handle declared in a SET DATABASE statement. g Specifies a cache buffer for the process attaching to a database. In SQL programs before a database can be opened with CONNECT, it must be declared with the SET DATABASE statement. isql does not use SET DATABASE. In SQL programs while the same CONNECT statement can open more than one database, use separate statements to keep code easy to read. When CONNECT attaches to a database, it uses the default character set (NONE), or one specified in a previous SET NAMES statement. In SQL programs the CACHE option changes the database cache size count (the total number of available buffers) from the default of 75. This option can be used to: g Sets a new default size for all databases listed in the CONNECT statement that do not already have a specific cache size. g Specifies a cache for a program that uses a single database. g Changes the cache for one database without changing the default for all databases used by the program. The size of the cache persists as long as the attachment is active. If a database is already attached through a multi-client server, an increase in cache size due to a new attachment persists until all the attachments end. A decrease in cache size does not affect databases that are already attached through a server. A subset of CONNECT features is available in isql: database file name, USER, and PASSWORD. isql can only be connected to one database at a time. Each time CONNECT is used to attach to a database, previous attachments are disconnected. Examples The following statement opens a database for use in isql. It uses all the CONNECT options available to isql: CONNECT ’employee.fdb’ USER ’ACCT_REC’ PASSWORD ’peanuts’; The next statement, from an embedded application, attaches to a database file stored in the host-language variable and assigns a previously declared database handle to it: EXEC SQL SET DATABASE DB1 = ’employee.fdb’; EXEC SQL CONNECT :db_file AS DB1; 46
CONNECT The following embedded SQL statement attaches to employee.fdb and allocates 150 cache buffers: EXEC SQL CONNECT ’accounts.fdb’ CACHE 150; The next embedded SQL statement connects the user to all databases specified with previous SET DATABASE statements: EXEC SQL CONNECT ALL USER ’ACCT_REC’ PASSWORD ’peanuts’ CACHE 50; The following embedded SQL statement attaches to the database, employee.fdb, with 80 buffers and database employee2.fdb with the default of 75 buffers: EXEC SQL CONNECT ’employee.fdb’ CACHE 80, ’employee2.fdb’; The next embedded SQL statement attaches to all databases and allocates 50 buffers: EXEC SQL CONNECT ALL CACHE 50; The following embedded SQL statement connects to EMP1 and v, setting the number of buffers for each to 80: EXEC SQL CONNECT EMP1 CACHE 80, EMP2 CACHE 80; The next embedded SQL statement connects to two databases identified by variable names, setting different user names and passwords for each: EXEC SQL CONNECT :orderdb AS DB1 USER ’ACCT_REC’ PASSWORD ’peanuts’, :salesdb AS DB2 USER ’ACCT_PAY’ PASSWORD ’payout’; See Also DISCONNECT, SET DATABASE, SET NAMES Se the Data Definition Guide for more information about cache buffers and the Operations Guide for more information about database security and isql. LANGUAGE REFERENCE 47
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE COUNT( ) Calculates the number of rows that satisfy a query’s search condition. Available in SQL, DSQL, and isql. Syntax COUNT ( * | [ALL] value | DISTINCT value) Argument Description * Retrieves the number of rows in a specified table, including NULL values ALL Counts all non-NULL values in a column DISTINCT Returns the number of unique, non-NULL values for the column val A column or expression Description COUNT() is an aggregate function that returns the number of rows that satisfy a query’s search condition. It can be used in views and joins as well as in tables. Example The following embedded SQL statement returns the number of unique currency values it encounters in the COUNTRY table: EXEC SQL SELECT COUNT (DISTINCT CURRENCY) INTO :cnt FROM COUNTRY; See Also AVG( ), MAX( ), MIN( ) SUM( ) 48
CREATE DATABASE CREATE DATABASE Creates a new database. Available in SQL, DSQL, and isql. Syntax CREATE {DATABASE | SCHEMA} ’filespec’ [USER ’username’ [PASSWORD ’password’]] [PAGE_SIZE [=] int] [LENGTH [=] int [PAGE[S]]] [DEFAULT CHARACTER SET charset] [<secondary_file>]; <secondary_file> = FILE ’filespec’ [<fileinfo>] [<secondary_file>] <fileinfo> = [LENGTH [=] int [PAGE[S]] | STARTING [AT [PAGE]] int } [<fileinfo>] IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description ‘filespec’ A new database file specification; file naming conventions are platform-specific USER ‘username’ Checks the username against valid user name and password combinations in the security database on the server where the database will reside • Windows client applications must provide a user name on attachment to a server • Any client application attaching to a database on NT must provide a user name on attachment PASSWORD ‘password’ Checks the password against valid user name and password combinations in the security database on the server where the database will reside; can be up to 8 characters • Windows client applications must provide a user name and password on attachment to a server • Any client application attaching to a database on NT must provide a password on attachment PAGE_SIZE [=] int Size, in bytes, for database pages int can be 1024 (default), 2048, 4096, or 8192 LANGUAGE REFERENCE 49
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description DEFAULT CHARACTER SET Sets default character set for a database charset charset is the name of a character set; if omitted, character set defaults to NONE FILE ‘filespec’ Names one or more secondary files to hold database pages after the primary file is filled. For databases created on remote servers, secondary file specifications cannot include a node name. STARTING [AT [PAGE]] int Specifies the starting page number for a secondary file. LENGTH [=] Specifies the length of a primary or secondary database file. Use for int [PAGE[S]] primary file only if defining a secondary file in the same statement. Description CREATE DATABASE creates a new, empty database and establishes the following characteristics for it: g The name of the primary file that identifies the database for users. By default, databases are contained in single files. g The name of any secondary files in which the database is stored. A database can reside in more than one disk file if additional file names are specified as secondary files. If a database is created on a remote server, secondary file specifications cannot include a node name. g The size of database pages. Increasing page size can improve performance for the following reasons: · Indexes work faster because the depth of the index is kept to a minimum. · Keeping large rows on a single page is more efficient. · Blob data is stored and retrieved more efficiently when it fits on a single page. If most transactions involve only a few rows of data, a smaller page size might be appropriate, since less data needs to be passed back and forth and less memory is used by the disk cache. g The number of pages in each database file. g The dialect of the database. The initial dialect of the database is the dialect of the client that creates it. For example, if you are using isql, either start it with the -sql_dialect n switch or issue the SET SQL DIALECT n command before issuing the CREATE DATABASE command. Typically, you would create all databases in dialect 3. Dialect 1 exists to ease the migration of legacy databases. 50
CREATE DATABASE Note To change the dialect of a database, use gfix or the Properties dialog in IBConsole. See the Migration chapter in Getting Started for information about migrating databases. g The character set used by the database. For a list of the character sets recognized by Firebird, see Chapter 8, “Character Sets and Collation Orders.” Choice of DEFAULT CHARACTER SET limits possible collation orders to a subset of all available collation orders. Given a specific character set, a specific collation order can be specified when data is selected, inserted, or updated in a column. If you do not specify a default character set, the character set defaults to NONE. Using character set NONE means that there is no character set assumption for columns; data is stored and retrieved just as you originally entered it. You can load any character set into a column defined with NONE, but you cannot load that same data into another column that has been defined with a different character set. In that case, no transliteration is performed between the source and destination character sets, and transliteration errors may occur during assignment. g System tables that describe the structure of the database. After creating the database, you define its tables, views, indexes, and system views as well as any triggers, generators, stored procedures, and UDFs that you need. IMPORTANT In DSQL, you must execute CREATE DATABASE EXECUTE IMMEDIATE. The database handle and transaction name, if present, must be initialized to zero prior to use. Read-only databases Databases are always created in read-write mode. You can change a table to read-only mode in wither of two ways: You can specify mode -read_only when you restore a backup or you can use gfix -mode read_only to change the mode of a table to read-only. See “Read-only databases” in Chapter 6: “Database Configuration and Maintenance” in the Operations Guide. About file sizes Firebird dynamically expands the last file in a database as needed until it reaches the 4GB limit. This applies to single-file database as well as to the last file of multifile databases. You should be aware that specifying a LENGTH for such files has no effect. Firebird database files are limited to 4GB. The total file size is the product of the number of database pages times the page size. The default page size is 1KB and the maximum page size is 8KB. However, Firebird files are small at creation time and increase in size as needed. The product of number of pages times page size represents a potential maximum size, not the size at creation. LANGUAGE REFERENCE 51
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Examples The following isql statement creates a database in the current directory using isql: CREATE DATABASE ’employee.fdb’; The next embedded SQL statement creates a database with a page size of 2048 bytes rather than the default of 1024: EXEC SQL CREATE DATABASE ’employee.fdb’ PAGE_SIZE 2048; The following embedded SQL statement creates a database stored in two files and specifies its default character set: EXEC SQL CREATE DATABASE ’employee.fdb’ DEFAULT CHARACTER SET ISO8859_1 FILE ’employee2.fdb’ STARTING AT PAGE 10001; See Also ALTER DATABASE, DROP DATABASE See the Data Definition Guide for more information about secondary files, character set specification, and collation order; see the Operations Guide for more information about page size. CREATE DOMAIN Creates a column definition that is global to the database. Available in SQL, DSQL, and isql. Syntax CREATE DOMAIN domain [AS] <datatype> [DEFAULT {literal | NULL | USER}] [NOT NULL] [CHECK (<dom_search_condition>)] [COLLATE collation]; <datatype> = {SMALLINT|INTEGER|FLOAT|DOUBLE PRECISION}[<array_dim>] | {DATE|TIME|TIMESTAMP}[<array_dim>] | {DECIMAL | NUMERIC} [(precision [, scale])] [<array_dim>] | {CHAR | CHARACTER | CHARACTER VARYING | VARCHAR} [(int)] [<array_dim>] [CHARACTER SET charname] | {NCHAR | NATIONAL CHARACTER | NATIONAL CHAR} [VARYING] [(int)] [<array_dim>] | BLOB [SUB_TYPE {int | subtype_name}] [SEGMENT SIZE int] [CHARACTER SET charname] | BLOB [(seglen [, subtype])] 52
CREATE DOMAIN <array_dim> = [[x:]y [, [x:]y …]] <dom_search_condition> = { VALUE <operator> value | VALUE [NOT] BETWEEN value AND value | VALUE [NOT] LIKE value [ESCAPE value] | VALUE [NOT] IN (value [, value …]) | VALUE IS [NOT] NULL | VALUE [NOT] CONTAINING value | VALUE [NOT] STARTING [WITH] value | (<dom_search_condition>) | NOT <dom_search_condition> | <dom_search_condition> OR <dom_search_condition> | <dom_search_condition> AND <dom_search_condition> } <operator> = {= | < | > | <= | >= | !< | !> | <> | !=} Note on the CREATE DOMAIN syntax g You cannot specify a COLLATE clause for Blob columns. g When declaring arrays, you must include the outermost brackets, shown below in bold. For example, the following statement creates a 5 by 5 two-dimensional array of strings, each of which is 6 characters long: my_array = varchar(6)[5,5] Use the colon (:) to specify an array with a starting point other than 1. The following example creates an array of integers that begins at 10 and ends at 20: my_array = integer[20:30] IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. LANGUAGE REFERENCE 53
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description domain Unique name for the domain datatype SQL datatype DEFAULT Specifies a default column value that is entered when no other entry is made; possible values are: literal—Inserts a specified string, numeric value, or date value NULL—Enters a NULL value USER—Enters the user name of the current user; column must be of compatible character type to use the default NOT NULL Specifies that the values entered in a column cannot be NULL CHECK (dom_search_condition) Creates a single CHECK constraint for the domain VALUE Placeholder for the name of a column eventually based on the domain COLLATE collation Specifies a collation sequence for the domain Description CREATE DOMAIN builds an inheritable column definition that acts as a template for columns defined with CREATE TABLE or ALTER TABLE. The domain definition contains a set of characteristics, which include: g Datatype g An optional default value g Optional disallowing of NULL values g An optional CHECK constraint g An optional collation clause The CHECK constraint in a domain definition sets a dom_search_condition that must be true for data entered into columns based on the domain. The CHECK constraint cannot reference any domain or column. Note Be careful not to create a domain with contradictory constraints, such as declaring a domain NOT NULL and assigning it a DEFAULT value of NULL. The datatype specification for a CHAR or VARCHAR text domain definition can include a CHARACTER SET clause to specify a character set for the domain. Otherwise, the domain uses the default database character set. For a complete list of character sets recognized by Firebird, see Chapter 8, “Character Sets and Collation Orders.” 54
CREATE DOMAIN If you do not specify a default character set, the character set defaults to NONE. Using character set NONE means that there is no character set assumption for columns; data is stored and retrieved just as you originally entered it. You can load any character set into a column defined with NONE, but you cannot load that same data into another column that has been defined with a different character set. In these cases, no transliteration is performed between the source and destination character sets, so errors can occur during assignment. The COLLATE clause enables specification of a particular collation order for CHAR, VARCHAR, and BLOB text datatypes. Choice of collation order is restricted to those supported for the domain’s given character set, which is either the default character set for the entire database, or a different set defined in the CHARACTER SET clause as part of the datatype definition. For a complete list of collation orders recognized by Firebird, see Chapter 8, “Character Sets and Collation Orders.” Columns based on a domain definition inherit all characteristics of the domain. The domain default, collation clause, and NOT NULL setting can be overridden when defining a column based on a domain. A column based on a domain can add additional CHECK constraints to the domain CHECK constraint. Examples The following isql statement creates a domain that must have a positive value greater than 1,000, with a default value of 9,999. The keyword VALUE substitutes for the name of a column based on this domain. CREATE DOMAIN CUSTNO AS INTEGER DEFAULT 9999 CHECK (VALUE > 1000); The next isql statement limits the values entered in the domain to four specific values: CREATE DOMAIN PRODTYPE AS VARCHAR(12) CHECK (VALUE IN (’software’, ’hardware’, ’other’, ’N/A’)); The following isql statement creates a domain that defines an array of CHAR datatype: CREATE DOMAIN DEPTARRAY AS CHAR(31) [4:5]; LANGUAGE REFERENCE 55
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE In the following isql example, the first statement creates a domain with USER as the default. The next statement creates a table that includes a column, ENTERED_BY, based on the USERNAME domain. CREATE DOMAIN USERNAME AS VARCHAR(20) DEFAULT USER; CREATE TABLE ORDERS (ORDER_DATE DATE, ENTERED_BY USERNAME, ORDER_AMT DECIMAL(8,2)); INSERT INTO ORDERS (ORDER_DATE, ORDER_AMT) VALUES (’1-MAY-93’, 512.36); The INSERT statement does not include a value for the ENTERED_BY column, so Firebird automatically inserts the user name of the current user, JSMITH: SELECT * FROM ORDERS; 1-MAY-93 JSMITH 512.36 The next isql statement creates a BLOB domain with a TEXT subtype that has an assigned character set: CREATE DOMAIN DESCRIPT AS BLOB SUB_TYPE TEXT SEGMENT SIZE 80 CHARACTER SET SJIS; See Also ALTER DOMAIN, ALTER TABLE, CREATE TABLE, DROP DOMAIN For more information about character set specification and collation orders, see the Data Definition Guide. 56
CREATE EXCEPTION CREATE EXCEPTION Creates a used-defined error and associated message for use in stored procedures and triggers. Available in DSQL and isql. Syntax CREATE EXCEPTION name ’message’; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name associated with the exception message; must be unique among exception names in the database ‘message’ Quoted string containing alphanumeric characters and punctuation; maximum length = 78 characters. Description CREATE EXCEPTION creates an exception, a user-defined error with an associated message. Exceptions may be raised in triggers and stored procedures. Exceptions are global to the database. The same message or set of messages is available to all stored procedures and triggers in an application. For example, a database can have English and French versions of the same exception messages and use the appropriate set as needed. When raised by a trigger or a stored procedure, an exception: g Terminates the trigger or procedure in which it was raised and undoes any actions performed (directly or indirectly) by it. g Returns an error message to the calling application. In isql, the error message appears on the screen, unless output is redirected. Exceptions may be trapped and handled with a WHEN statement in a stored procedure or trigger. Examples This isql statement creates the exception, UNKNOWN_EMP_ID: CREATE EXCEPTION UNKNOWN_EMP_ID ’Invalid employee number or project id.’; The following statement from a stored procedure raises the previously created exception when SQLCODE -530 is set, which is a violation of a FOREIGN KEY constraint: . . . WHEN SQLCODE -530 DO LANGUAGE REFERENCE 57
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE EXCEPTION UNKNOWN_EMP_ID; . . . See Also ALTER EXCEPTION, ALTER PROCEDURE, ALTER TRIGGER, CREATE PROCEDURE, CREATE TRIGGER, DROP EXCEPTION For more information on creating, raising, and handling exceptions, see the Data Definition Guide. CREATE GENERATOR Declares a generator to the database. Available in SQL, DSQL, and isql. Syntax CREATE GENERATOR name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name for the generator Description CREATE GENERATOR declares a generator to the database and sets its starting value to zero. A generator is a sequential number that can be automatically inserted in a column with the GEN_ID() function. A generator is often used to ensure a unique value in a PRIMARY KEY, such as an invoice number, that must uniquely identify the associated row. A database can contain any number of generators. Generators are global to the database, and can be used and updated in any transaction. Firebird does not assign duplicate generator values across transactions. You can use SET GENERATOR to set or change the value of an existing generator when writing triggers, procedures, or SQL statements that call GEN_ID(). Note There is no “drop generator” statement. To remove a generator, delete it from the system table. For example: DELETE FROM RDB$GENERATOR WHERE RDB$GENERATOR_NAME = ‘EMPNO_GEN’; Example The following isql script fragment creates the generator, EMPNO_GEN, and the trigger, CREATE_EMPNO. The trigger uses the generator to produce sequential numeric keys, incremented by 1, for the NEW.EMPNO column: CREATE GENERATOR EMPNO_GEN; COMMIT; 58
CREATE INDEX SET TERM !! ; CREATE TRIGGER CREATE_EMPNO FOR EMPLOYEES BEFORE INSERT POSITION 0 AS BEGIN NEW.EMPNO = GEN_ID(EMPNO_GEN, 1); END SET TERM ; !! IMPORTANT Because each statement in a stored procedure body must be terminated by a semicolon, you must define a different symbol to terminate the CREATE TRIGGER in isql. Use SET TERM before CREATE TRIGGER to specify a terminator other than a semicolon. After CREATE TRIGGER, include another SET TERM to change the terminator back to a semicolon. See Also GEN_ID( ), SET GENERATOR CREATE INDEX Creates an index on one or more columns in a table. Available in SQL, DSQL, and isql. Syntax CREATE [UNIQUE] [ASC[ENDING] | DESC[ENDING]] INDEX index ON table (col [, col …]); IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description UNIQUE Prevents insertion or updating of duplicate values into indexed columns ASC[ENDING] Sorts columns in ascending order, the default order if none is specified DESC[ENDING] Sorts columns in descending order index Unique name for the index table Name of the table on which the index is defined col Column in table to index Description Creates an index on one or more columns in a table. Use CREATE INDEX to improve speed of data access. Using an index for columns that appear in a WHERE clause may improve search performance. LANGUAGE REFERENCE 59
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE IMPORTANT You cannot index Blob columns or arrays. A UNIQUE index cannot be created on a column or set of columns that already contains duplicate or NULL values. ASC and DESC specify the order in which an index is sorted. For faster response to queries that require sorted values, use the index order that matches the query’s ORDER BY clause. Both an ASC and a DESC index can be created on the same column or set of columns to access data in different orders. Tip To improve index performance, use SET STATISTICS to recompute index selectivity, or rebuild the index by making it inactive, then active with sequential calls to ALTER INDEX. Examples The following isql statement creates a unique index: CREATE UNIQUE INDEX PRODTYPEX ON PROJECT (PRODUCT, PROJ_NAME); The next isql statement creates a descending index: CREATE DESCENDING INDEX CHANGEX ON SALARY_HISTORY (CHANGE_DATE); The following isql statement creates a two-column index: CREATE INDEX NAMEX ON EMPLOYEE (LAST_NAME, FIRST_NAME); See Also ALTER INDEX, DROP INDEX, SELECT, SET STATISTICS 60
CREATE PROCEDURE CREATE PROCEDURE Creates a stored procedure, its input and output parameters, and its actions. Available in DSQL, and isql. Syntax CREATE PROCEDURE name [(param <datatype> [, param <datatype> …])] [RETURNS <datatype> [, param <datatype> …])] AS <procedure_body> [terminator] <procedure_body> = [<variable_declaration_list>] <block> <variable_declaration_list> = DECLARE VARIABLE var <datatype>; [DECLARE VARIABLE var <datatype>; …] <block> = BEGIN <compound_statement> [<compound_statement> …] END <compound_statement> = {<block> | statement;} <datatype> = SMALLINT | INTEGER | FLOAT | DOUBLE PRECISION | {DECIMAL | NUMERIC} [(precision [, scale])] | {DATE | TIME | TIMESTAMP) | {CHAR | CHARACTER | CHARACTER VARYING | VARCHAR} [(int)] [CHARACTER SET charname] | {NCHAR | NATIONAL CHARACTER | NATIONAL CHAR} [VARYING] [(int)] LANGUAGE REFERENCE 61
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description name Name of the procedure. Must be unique among procedure, table, and view names in the database param datatype Input parameters that the calling program uses to pass values to the procedure: param: Name of the input parameter, unique for variables in the procedure datatype: An Firebird datatype RETURNS param datatype Output parameters that the procedure uses to return values to the calling program: param: Name of the output parameter, unique for variables within the procedure datatype: An Firebird datatype The procedure returns the values of output parameters when it reaches a SUSPEND statement in the procedure body AS Keyword that separates the procedure header and the procedure body DECLARE VARIABLE Declares local variables used only in the procedure; must be var datatype preceded by DECLARE VARIABLE and followed by a semicolon (;). var is the name of the local variable, unique for variables in the procedure. statement Any single statement in Firebird procedure and trigger language; must be followed by a semicolon (;) except for BEGIN and END statements terminator Terminator defined by SET TERM • Signifies the end of the procedure body;• Used only in isql Description CREATE PROCEDURE defines a new stored procedure to a database. A stored procedure is a self-contained program written in Firebird procedure and trigger language, and stored as part of a database’s metadata. Stored procedures can receive input parameters from and return values to applications. Firebird procedure and trigger language includes all SQL data manipulation statements and some powerful extensions, including IF … THEN … ELSE, WHILE … DO, FOR SELECT … DO, exceptions, and error handling. 62
CREATE PROCEDURE There are two types of procedures: g Select procedures that an application can use in place of a table or view in a SELECT statement. A select procedure must be defined to return one or more values, or an error will result. g Executable procedures that an application can call directly, with the EXECUTE PROCEDURE statement. An executable procedure need not return values to the calling program. A stored procedure is composed of a header and a body. The procedure header contains: g The name of the stored procedure, which must be unique among procedure and table names in the database. g An optional list of input parameters and their datatypes that a procedure receives from the calling program. g RETURNS followed by a list of output parameters and their datatypes if the procedure returns values to the calling program. The procedure body contains: g An optional list of local variables and their datatypes. g A block of statements in Firebird procedure and trigger language, bracketed by BEGIN and END. A block can itself include other blocks, so that there may be many levels of nesting. IMPORTANT Because each statement in a stored procedure body must be terminated by a semicolon, you must define a different symbol to terminate the CREATE PROCEDURE statement in isql. Use SET TERM before CREATE PROCEDURE to specify a terminator other than a semicolon. After the CREATE PROCEDURE statement, include another SET TERM to change the terminator back to a semicolon. Firebird does not allow database changes that affect the behavior of an existing stored procedure (for example, DROP TABLE or DROP EXCEPTION). To see all procedures defined for the current database or the text and parameters of a named procedure, use the isql internal commands SHOW PROCEDURES or SHOW PROCEDURE procedure. Firebird procedure and trigger language is a complete programming language for stored procedures and triggers. It includes: g SQL data manipulation statements: INSERT, UPDATE, DELETE, and singleton SELECT. g SQL operators and expressions, including generators and UDFs that are linked with the database. LANGUAGE REFERENCE 63
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE g Extensions to SQL, including assignment statements, control-flow statements, context variables (for triggers), event-posting statements, exceptions, and error-handling statements. The following table summarizes language extensions for stored procedures. For a complete description of each statement, see Chapter 3, “Procedures and Triggers.” Statement Description BEGIN … END Defines a block of statements that executes as one • The BEGIN keyword starts the block; the END keyword terminates it• Neither should end with a semicolon variable = expression Assignment statement: assigns the value of expression to variable, a local variable, input parameter, or output parameter /* comment_text */ Programmer’s comment, where comment_text can be any number of lines of text EXCEPTION exception_name Raises the named exception: an exception is a user-defined error that returns an error message to the calling application unless handled by a WHEN statement EXECUTE PROCEDURE Executes stored procedure, proc_name, with the listed input proc_name [var [, var …]] arguments, returning values in the listed output arguments [RETURNING_VALUES following RETURNING_VALUES; input and output arguments must be var [, var …]] local variables EXIT Jumps to the final END statement in the procedure FOR select_statement Repeats the statement or block following DO for every qualifying row DO compound_statement retrieved by select_statement select_statement is like a normal SELECT statement, except that there is an INTO clause that is required and which must come last compound_statement Either a single statement in procedure and trigger language or a block of statements bracketed by BEGIN and END IF (condition) Tests condition, and if it is TRUE, performs the statement or block THEN compound_statement following THEN; otherwise, performs the statement or block [ELSE compound_statement] following ELSE, if present condition: a Boolean expression (TRUE, FALSE, or UNKNOWN), generally two expressions as operands of a comparison operator TABLE 2.7 Procedure and trigger language extensions 64
CREATE PROCEDURE Statement Description NEW.column New context variable that indicates a new column value in an INSERT or UPDATE operation OLD.column Old context variable that indicates a column value before an UPDATE or DELETE operation POST_EVENT event_name | col Posts the event, event_name, or uses the value in col as an event name SUSPEND In a SELECT procedure: • Suspends execution of procedure until next FETCH is issued by the calling application • Returns output values, if any, to the calling application• Not recommended for executable procedures WHILE (condition) While condition is TRUE, keep performing compound_statement DO compound_statement • Tests condition, andperforms compound_statement if condition is TRUE • Repeats this sequence until condition is no longer TRUE WHEN {error [, error …] | ANY} Error-handling statement: when one of the specified errors occurs, DO compound_statement performs compound_statement • WHEN statements, if present, must come at the end of a block, just before END • error: EXCEPTION exception_name, SQLCODE errcode or GDSCODE number • ANY: Handles any errors TABLE 2.7 Procedure and trigger language extensions (continued) Examples The following procedure, SUB_TOT_BUDGET, takes a department number as its input parameter, and returns the total, average, minimum, and maximum budgets of departments with the specified HEAD_DEPT. /* Compute total, average, smallest, and largest department budget. *Parameters: * department id * *Returns: * total budget * average budget LANGUAGE REFERENCE 65
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE * min budget * max budget */ SET TERM !! ; CREATE PROCEDURE SUB_TOT_BUDGET (HEAD_DEPT CHAR(3)) RETURNS (tot_budget DECIMAL(12, 2), avg_budget DECIMAL(12, 2), min_budget DECIMAL(12, 2), max_budget DECIMAL(12, 2)) AS BEGIN SELECT SUM(BUDGET), AVG(BUDGET), MIN(BUDGET), MAX(BUDGET) FROM DEPARTMENT WHERE HEAD_DEPT = :head_dept INTO :tot_budget, :avg_budget, :min_budget, :max_budget; EXIT; END !! SET TERM ; !! The following select procedure, ORG_CHART, displays an organizational chart: /* Display an org-chart. * * Parameters: * -- * Returns: * parent department * department name * department manager * manager’s job title * number of employees in the department */ CREATE PROCEDURE ORG_CHART RETURNS (HEAD_DEPT CHAR(25), DEPARTMENT CHAR(25), MNGR_NAME CHAR(20), TITLE CHAR(5), EMP_CNT INTEGER) AS DECLARE VARIABLE mngr_no INTEGER; DECLARE VARIABLE dno CHAR(3); 66
CREATE PROCEDURE BEGIN FOR SELECT H.DEPARTMENT, D.DEPARTMENT, D.MNGR_NO, D.DEPT_NO FROM DEPARTMENT D LEFT OUTER JOIN DEPARTMENT H ON D.HEAD_DEPT = H.DEPT_NO ORDER BY D.DEPT_NO INTO :head_dept, :department, :mngr_no, :dno DO BEGIN IF (:mngr_no IS NULL) THEN BEGIN MNGR_NAME = ’--TBH--’; TITLE = ’’; END ELSE SELECT FULL_NAME, JOB_CODE FROM EMPLOYEE WHERE EMP_NO = :mngr_no INTO :mngr_name, :title; SELECT COUNT(EMP_NO) FROM EMPLOYEE WHERE DEPT_NO = :dno INTO :emp_cnt; SUSPEND; END END !! When ORG_CHART is invoked, for example in the following isql statement: SELECT * FROM ORG_CHART it displays the department name for each department, which department it is in, the department manager’s name and title, and the number of employees in the department. LANGUAGE REFERENCE 67
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE HEAD_DEPT DEPARTMENT MGR_NAME TITLE EMP_CNT ===================== =================== ================ ==== ======= Corporate Bender, Oliver H. CEO 2 Headquarters Corporate Sales and Marketing MacDonald, Mary S.VP 2 Headquarters Sales and Marketing Pacific Rim Baldwin, Janet Sales 2 Headquarters Pacific Rim Field Office: Japan Yamamoto, Takashi SRep 2 Headquarters Pacific Rim Field Office: —TBH— 0 Headquarters Singapore ORG_CHART must be used as a select procedure to display the full organization. If called with EXECUTE PROCEDURE, the first time it encounters the SUSPEND statement, it terminates, returning the information for Corporate Headquarters only. See Also ALTER EXCEPTION, ALTER PROCEDURE, CREATE EXCEPTION, DROP EXCEPTION, DROP PROCEDURE, EXECUTE PROCEDURE, SELECT For more information on creating and using procedures, see the Data Definition Guide. For a complete description of the statements in procedure and trigger language, see Chapter 3, “Procedures and Triggers.” 68
CREATE ROLE CREATE ROLE Creates a role. Syntax CREATE ROLE rolename; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description rolename Name associated with the role; must be unique among role names in the database Description Roles created with CREATE ROLE can be granted privileges just as users can. These roles can be granted to users, who then inherit the privilege list that has been granted to the role. Users must specify the role at connect time. Use GRANT to grant privileges (ALL, SELECT, INSERT, UPDATE, DELETE, EXECUTE, REFERENCES) to a role and to grant a role to users. Use REVOKE to revoke them. Example The following statement creates a role called “administrator.” CREATE ROLE administrator; See Also GRANT, REVOKE, DROP ROLE CREATE SHADOW Creates one or more duplicate, in-sync copies of a database. Available in SQL, DSQL, and isql. Syntax CREATE SHADOW set_num [AUTO | MANUAL] [CONDITIONAL] ’filespec’ [LENGTH [=] int [PAGE[S]]] [<secondary_file>]; <secondary_file> = FILE ’filespec’ [<fileinfo>] [<secondary_file>] <fileinfo> = LENGTH [=] int [PAGE[S]] | STARTING [AT [PAGE]] int [<fileinfo>] IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. LANGUAGE REFERENCE 69
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description set_num Positive integer that designates a shadow set to which all subsequent files listed in the statement belong AUTO Specifies the default access behavior for databases in the event no shadow is available • All attachments and accesses succeed• Deletes all references to the shadow and detaches the shadow file MANUAL Specifies that database attachments and accesses fail until a shadow becomes available, or until all references to the shadow are removed from the database CONDITIONAL Creates a new shadow, allowing shadowing to continue if the primary shadow becomes unavailable or if the shadow replaces the database due to disk failure ‘filespec’br> Explicit path name and file name for the shadow file; must be a local filesystem and must not include a node name or be on a neworked filesystem LENGTH [=] int [PAGE[S]] Length in database pages of an additional shadow file; page size is determined by the page size of the database itself secondary_file Specifies the length of a primary or secondary shadow file; use for primary file only if defining a secondary file in the same statement STARTING [AT [PAGE]] int Starting page number at which a secondary shadow file begins Description CREATE SHADOW is used to guard against loss of access to a database by establishing one or more copies of the database on secondary storage devices. Each copy of the database consists of one or more shadow files, referred to as a shadow set. Each shadow set is designated by a unique positive integer. Disk shadowing has three components: g A database to shadow. g The RDB$FILES system table, which lists shadow files and other information about the database. g A shadow set, consisting of one or more shadow files. 70
CREATE SHADOW When CREATE SHADOW is issued, a shadow is established for the database most recently attached by an application. A shadow set can consist of one or multiple files. In case of disk failure, the database administrator (DBA) activates the disk shadow so that it can take the place of the database. If CONDITIONAL is specified, then when the DBA activates the disk shadow to replace an actual database, a new shadow is established for the database. If a database is larger than the space available for a shadow on one disk, use the secondary_file option to define multiple shadow files. Multiple shadow files can be spread over several disks. Tip To add a secondary file to an existing disk shadow, drop the shadow with DROP SHADOW and use CREATE SHADOW to recreate it with the desired number of files. Examples The following isql statement creates a single, automatic shadow file for employee.fdb: CREATE SHADOW 1 AUTO ’employee.shd’; The next isql statement creates a conditional, single, automatic shadow file for employee.fdb: CREATE SHADOW 2 CONDITIONAL ’employee.shd’ LENGTH 1000; The following isql statements create a multiple-file shadow set for the employee.fdb database. The first statement specifies starting pages for the shadow files; the second statement specifies the number of pages for the shadow files. CREATE SHADOW 3 AUTO ’employee.sh1’ FILE ’employee.sh2’ STARTING AT PAGE 1000 FILE ’employee.sh3’ STARTING AT PAGE 2000; CREATE SHADOW 4 MANUAL ’employee.sdw’ LENGTH 1000 FILE ’employee.sh1’ LENGTH 1000 FILE ’employee.sh2’; See Also DROP SHADOW For more information about using shadows, see the Operations Guide or the Data Definition Guide. LANGUAGE REFERENCE 71
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE CREATE TABLE Creates a new table in an existing database. Available in SQL, DSQL, and isql. Syntax CREATE TABLE table [EXTERNAL [FILE] ’filespec’] (<col_def> [, <col_def> | <tconstraint> …]); <col_def> = col {<datatype> | COMPUTED [BY] (<expr>) | domain} [DEFAULT {literal | NULL | USER}] [NOT NULL] [<col_constraint>] [COLLATE collation] <datatype> = {SMALLINT | INTEGER | FLOAT | DOUBLE PRECISION}[<array_dim>] | (DATE | TIME | TIMESTAMP}[<array_dim>] | {DECIMAL | NUMERIC} [(precision [, scale])] [<array_dim>] | {CHAR | CHARACTER | CHARACTER VARYING | VARCHAR} [(int)] [<array_dim>] [CHARACTER SET charname] | {NCHAR | NATIONAL CHARACTER | NATIONAL CHAR} [VARYING] [(int)] [<array_dim>] | BLOB [SUB_TYPE {int | subtype_name}] [SEGMENT SIZE int] [CHARACTER SET charname] | BLOB [(seglen [, subtype])]<array_dim> = [[x:]y [, [x:]y …]] <expr> = A valid SQL expression that results in a single value. <col_constraint> = [CONSTRAINT constraint] { UNIQUE | PRIMARY KEY | REFERENCES other_table [(other_col [, other_col …])] [ON DELETE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] [ON UPDATE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] | CHECK (<search_condition>)} <tconstraint> = [CONSTRAINT constraint] {{PRIMARY KEY | UNIQUE} (col [, col …]) | FOREIGN KEY (col [, col …]) REFERENCES other_table [ON DELETE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] [ON UPDATE {NO ACTION|CASCADE|SET DEFAULT|SET NULL}] | CHECK (<search_condition>)} 72
CREATE TABLE <search_condition> = <val> <operator> {<val> | (<select_one>)} | <val> [NOT] BETWEEN <val> AND <val> | <val> [NOT] LIKE <val> [ESCAPE <val>] | <val> [NOT] IN (<val> [, <val> …] | <select_list>) | <val> IS [NOT] NULL | <val> {>= | <=} | <val> [NOT] {= | < | >} | {ALL | SOME | ANY} (<select_list>) | EXISTS (<select_expr>) | SINGULAR (<select_expr>) | <val> [NOT] CONTAINING <val> | <val> [NOT] STARTING [WITH] <val> | (<search_condition>) | NOT <search_condition> | <search_condition> OR <search_condition> | <search_condition> AND <search_condition> <val> = { col [<array_dim>] | :variable | <constant> | <expr> | <function> | udf ([<val> [, <val> …]]) | NULL | USER | RDB$DB_KEY | ? } [COLLATE collation] <constant> = num | 'string' | charsetname 'string' <function> = COUNT (* | [ALL] <val> | DISTINCT <val>) | SUM ([ALL] <val> | DISTINCT <val>) | AVG ([ALL] <val> | DISTINCT <val>) | MAX ([ALL] <val> | DISTINCT <val>) | MIN ([ALL] <val> | DISTINCT <val>) | CAST (<val> AS <datatype>) | UPPER (<val>) | GEN_ID (generator, <val>) <operator> = {= | < | > | <= | >= | !< | !> | <> | !=} <select_one> = SELECT on a single column; returns exactly one value. <select_list> = SELECT on a single column; returns zero or more values. <select_expr> = SELECT on a list of values; returns zero or more values. LANGUAGE REFERENCE 73
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Notes on the CREATE TABLE statement g When declaring arrays, you must include the outermost brackets, shown below in bold. For example, the following statement creates a 5 by 5 two-dimensional array of strings, each of which is 6 characters long: my_array VARCHAR(6)[5,5] Use the colon (:) to specify an array with a starting point other than 1. The following example creates an array of integers that begins at 10 and ends at 20: my_array INTEGER[10:20] g In SQL and isql, you cannot use val as a parameter placeholder (like “?”). g In DSQL and isql, val cannot be a variable. g You cannot specify a COLLATE clause for Blob columns. g expr is any complex SQL statement or equation that produces a single value. Argument Description table Name for the table; must be unique among table and procedure names in the database EXTERNAL [FILE] ‘filespec’ Declares that data for the table under creation resides in a table or file outside the database; filespec is the complete file specification of the external file or table col Name for the table column; unique among column names in the table datatype SQL datatype for the column; see “Datatypes” on page 19 COMPUTED [BY] (expr) Specifies that the value of the column’s data is calculated from expr at runtime and is therefore not allocated storage space in the database • expr can be any arithmetic expression valid for the datatypes in the expression • Any columns referenced in expr must exist before they can be used in expr • expr cannot reference Blob columns• expr must return a single value, and cannot return an array domain Name of an existing domain 74
CREATE TABLE Argument Description DEFAULT Specifies a default column value that is entered when no other entry is made; possible values are: • literal: Inserts a specified string, numeric value, or date value• NULL: Enters a NULL value• USER: Enters the user name of the current user. Column must be of compatible text type to use the default Defaults set at column level override defaults set at the domain level. CONSTRAINT constraint Name of a column or table constraint; the constraint name must be unique within the table constraint_def Specifies the kind of column constraint; valid options are UNIQUE, PRIMARY KEY, CHECK, and REFERENCES REFERENCES Specifies that the column values are derived from column values in another table; if you do not specify column names, Firebird looks for a column with the same name as the referencing column in the referenced table ON DELETE | Used with REFERENCES: Changes a foreign key whenever the referenced ON UPDATE primary key changes; valid options are: • [Default] NO ACTION: Does not change the foreign key; may cause the primary key update to fail due to referential integrity checks • CASCADE: For ON DELETE, deletes the corresponding foreign key; for ON UPDATE, updates the corresponding foreign key to the new value of the primary key • SET NULL: Sets all the columns of the corresponding foreign key to NULL• SET DEFAULT: Sets every column of the corresponding foreign key is set to its default value in effect when the referential integrity constraint is defined; when the default for a foreign column changes after the referential integrity constraint is defined, the change does not have an effect on the default value used in the referential integrity constraint CHECK search_condition An attempt to enter a new value in the column fails if the value does not meet the search_condition COLLATE collation Establishes a default sorting behavior for the column; see Chapter 8, “Character Sets and Collation Orders” for more information LANGUAGE REFERENCE 75
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Description CREATE TABLE establishes a new table, its columns, and integrity constraints in an existing database. The user who creates a table is the table’s owner and has all privileges for it, including the ability to GRANT privileges to other users, triggers, and stored procedures. g CREATE TABLE supports several options for defining columns: · Local columns specify the name and datatype for data entered into the column. · Computed columns are based on an expression. Column values are computed each time the table is accessed. If the datatype is not specified, Firebird calculates an appropriate one. Columns referenced in the expression must exist before the column can be defined. · Domain-based columns inherit all the characteristics of a domain, but the column definition can include a new default value, a NOT NULL attribute, additional CHECK constraints, or a collation clause that overrides the domain definition. It can also include additional column constraints. · The datatype specification for a CHAR, VARCHAR, or Blob text column definition can include a CHARACTER SET clause to specify a particular character set for the single column. Otherwise, the column uses the default database character set. If the database character set is changed, all columns subsequently defined have the new character set, but existing columns are not affected. For a complete list of character sets recognized by Firebird, see Chapter 8, “Character Sets and Collation Orders.” · If you do not specify a default character set, the character set defaults to NONE. Using character set NONE means that there is no character set assumption for columns; data is stored and retrieved just as you originally entered it. You can load any character set into a column defined with NONE, but you cannot load that same data into another column that has been defined with a different character set. In this case, no transliteration is performed between the source and destination character sets, and errors may occur during assignment. · The COLLATE clause enables specification of a particular collation order for CHAR, VARCHAR, and Blob text datatypes. Choice of collation order is restricted to those supported for the column’s given character set, which is either the default character set for the entire database, or a different set defined in the CHARACTER SET clause as part of the datatype definition. For a complete list of collation orders recognized by Firebird, see Chapter 8, “Character Sets and Collation Orders.” g NOT NULL is an attribute that prevents the entry of NULL or unknown values in column. NOT NULL affects all INSERT and UPDATE operations on a column. IMPORTANT A DECLARE TABLE must precede CREATE TABLE in embedded applications if the same SQL program both creates a table and inserts data in the table. 76
CREATE TABLE g The EXTERNAL FILE option creates a table whose data resides in an external file, rather than in the Firebird database. Use this option to: · Define an Firebird table composed of data from an external source, such as data in files managed by other operating systems or in non-database applications. · Transfer data to an existing Firebird table from an external file. Referential integrity constraints g You can define integrity constraints at the time you create a table. These constraints are rules that validate data entries by enforcing column-to-table and table-to-table relationships. They span all transactions that access the database and are automatically maintained by the system. CREATE TABLE supports the following integrity constraints: g A PRIMARY KEY is one or more columns whose collective contents are guaranteed to be unique. A PRIMARY KEY column must also define the NOT NULL attribute. A table can have only one primary key. g UNIQUE keys ensure that no two rows have the same value for a specified column or ordered set of columns. A unique column must also define the NOT NULL attribute. A table can have one or more UNIQUE keys. A UNIQUE key can be referenced by a FOREIGN KEY in another table. g Referential constraints (REFERENCES) ensure that values in the specified columns (known as the foreign key) are the same as values in the referenced UNIQUE or PRIMARY KEY columns in another table. The UNIQUE or PRIMARY KEY columns in the referenced table must be defined before the REFERENCES constraint is added to the secondary table. REFERENCES has ON DELETE and ON UPDATE clauses that define the action on the foreign key when the referenced primary key is updated or deleted. The values for ON UPDATE and ON DELETE are as follows: LANGUAGE REFERENCE 77
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Action specified Effect on foreign key NO ACTION [Default] The foreign key does not change. This may cause the primary key update or delete to fail due to referential integrity checks. CASCADE The corresponding foreign key is updated or deleted as appropriate to the new value of the primary key. SET DEFAULT Every column of the corresponding foreign key is set to its default value. If the default value of the foreign key is not found in the primary key, the update or delete on the primary key fails. The default value is the one in effect when the referential integrity constraint was defined. When the default for a foreign key column is changed after the referential integrity constraint is set up, the change does not have an effect on the default value used in the referential integrity constraint. SET NULL Every column of the corresponding foreign key is set to NULL. g You can create a FOREIGN KEY reference to a table that is owned by someone else only if that owner has explicitly granted you REFERENCES privilege on that table. Any user who updates your foreign key table must have REFERENCES or SELECT privileges on the referenced primary key table. g CHECK constraints enforce a search_condition that must be true for inserts or updates to the specified table. search_condition can require a combination or range of values or can compare the value entered with data in other columns. Note Specifying USER as the value for a search_condition references the login of the user who is attempting to write to the referenced table. g Creating PRIMARY KEY and FOREIGN KEY constraints requires exclusive access to the database. g For unnamed constraints, the system assigns a unique constraint name stored in the RDB$RELATION_CONSTRAINTS system table. Note Constraints are not enforced on expressions. Examples The following isql statement creates a simple table with a PRIMARY KEY: CREATE TABLE COUNTRY (COUNTRY COUNTRYNAME NOT NULL PRIMARY KEY, CURRENCY VARCHAR(10) NOT NULL); 78
CREATE TABLE The next isql statement creates both a column-level and a table-level UNIQUE constraint: CREATE TABLE STOCK ( MODEL SMALLINT NOT NULL UNIQUE, MODELNAME CHAR(10) NOT NULL, ITEMID INTEGER NOT NULL, CONSTRAINT MOD_UNIQUE UNIQUE (MODELNAME, ITEMID)); The following isql statemnent illustrates table-level PRIMARY KEY, FOREIGN KEY, and CHECK constraints. The PRIMARY KEY constraint is based on three columns. This example also illustrates creating an array column of VARCHAR. CREATE TABLE JOB ( JOB_CODE JOBCODE NOT NULL, JOB_GRADE JOBGRADE NOT NULL, JOB_COUNTRY COUNTRYNAME NOT NULL, JOB_TITLE VARCHAR(25) NOT NULL, MIN_SALARY SALARY NOT NULL, MAX_SALARY SALARY NOT NULL, JOB_REQUIREMENT BLOB(400,1), LANGUAGE_REQ VARCHAR(15) [5], PRIMARY KEY (JOB_CODE, JOB_GRADE, JOB_COUNTRY), FOREIGN KEY (JOB_COUNTRY) REFERENCES COUNTRY (COUNTRY), CHECK (MIN_SALARY < MAX_SALARY)); In the next example, the F2 column in table T2 is a foreign key that references table T1 through T1’s primary key P1. When a row in T1 changes, that change propagates to all affected rows in table T2. When a row in T1 is deleted, all affected rows in the F2 column of table T2 are set to NULL. CREATE TABLE T1 (P1 INTEGER NOT NULL PRIMARY KEY); CREATE TABLE T2 (F2 INTEGER FOREIGN KEY REFERENCES T1.P1 ON UPDATE CASCADE ON DELETE SET NULL); The next isql statement creates a table with a calculated column: CREATE TABLE SALARY_HISTORY ( EMP_NO EMPNO NOT NULL, CHANGE_DATE DATE DEFAULT ’NOW’ NOT NULL, UPDATER_ID VARCHAR(20) NOT NULL, OLD_SALARY SALARY NOT NULL, PERCENT_CHANGE DOUBLE PRECISION DEFAULT 0 NOT NULL CHECK (PERCENT_CHANGE BETWEEN -50 AND 50), LANGUAGE REFERENCE 79
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE NEW_SALARY COMPUTED BY (OLD_SALARY + OLD_SALARY * PERCENT_CHANGE / 100), PRIMARY KEY (EMP_NO, CHANGE_DATE, UPDATER_ID), FOREIGN KEY (EMP_NO) REFERENCES EMPLOYEE (EMP_NO)); In the following isql statement the first column retains the default collating order for the database’s default character set. The second column has a different collating order, and the third column definition includes a character set and a collating order. CREATE TABLE BOOKADVANCE ( BOOKNO CHAR(6), TITLE CHAR(50) COLLATE ISO8859_1, EUROPUB CHAR(50) CHARACTER SET ISO8859_1 COLLATE FR_FR); See Also CREATE DOMAIN, DECLARE TABLE, GRANT, REVOKE For more information on creating metadata, using integrity constraints, external tables, datatypes, collation order, and character sets, see the Data Definition Guide. CREATE TRIGGER Creates a trigger, including when it fires, and what actions it performs. Available in DSQL, and isql. Syntax CREATE TRIGGER name FOR table [ACTIVE | INACTIVE] {BEFORE | AFTER} {DELETE | INSERT | UPDATE} [POSITION number] AS <trigger_body> terminator <trigger_body> = [<variable_declaration_list>] <block> <variable_declaration_list> = DECLARE VARIABLE variable <datatype>; [DECLARE VARIABLE variable <datatype>; …] <block> = BEGIN <compound_statement> [<compound_statement> …] END <datatype> = SMALLINT | INTEGER 80
CREATE TRIGGER | FLOAT | DOUBLE PRECISION | {DECIMAL | NUMERIC} [(precision [, scale])] | {DATE | TIME | TIMESTAMP) | {CHAR | CHARACTER | CHARACTER VARYING | VARCHAR} [(int)] [CHARACTER SET charname] | {NCHAR | NATIONAL CHARACTER | NATIONAL CHAR} [VARYING] [(int)] <compound_statement> = {<block> | statement;} Argument Description name Name of the trigger; must be unique in the database table Name of the table or view that causes the trigger to fire when the specified operation occurs on the table or view ACTIVE|INACTIVE Optional. Specifies trigger action at transaction end: • ACTIVE: [Default] Trigger takes effect• INACTIVE: Trigger does not take effect BEFORE|AFTER Required. Specifies whether the trigger fires: • BEFORE: Before associated operation• AFTER: After associated operationAssociated operations are DELETE, INSERT, or UPDATE DELETE|INSERT Specifies the table operation that causes the trigger to fire |UPDATE POSITION number Specifies firing order for triggers before the same action or after the same action; number must be an integer between 0 and 32,767, inclusive. • Lower-number triggers fire first• Default: 0 = first trigger to fire• Triggers for a table need not be consecutive; triggers on the same action with the same position number will fire in random order. LANGUAGE REFERENCE 81
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description DECLARE VARIABLE Declares local variables used only in the trigger. Each declaration must var datatype be preceded by DECLARE VARIABLE and followed by a semicolon (;). • var: Local variable name, unique in the trigger• datatype: The datatype of the local variable statement Any single statement in Firebird procedure and trigger language; each statement except BEGIN and END must be followed by a semicolon (;) terminator Terminator defined by the SET TERM statement; signifies the end of the trigger body. Used in isql only. Description CREATE TRIGGER defines a new trigger to a database. A trigger is a self-contained program associated with a table or view that automatically performs an action when a row in the table or view is inserted, updated, or deleted. A trigger is never called directly. Instead, when an application or user attempts to INSERT, UPDATE, or DELETE a row in a table, any triggers associated with that table and operation automatically execute, or fire. Triggers defined for UPDATE on non-updatable views fire even if no update occurs. A trigger is composed of a header and a body. The trigger header contains: g A trigger name, unique within the database, that distinguishes the trigger from all others. g A table name, identifying the table with which to associate the trigger. g Statements that determine when the trigger fires. The trigger body contains: g An optional list of local variables and their datatypes. g A block of statements in Firebird procedure and trigger language, bracketed by BEGIN and END. These statements are performed when the trigger fires. A block can itself include other blocks, so that there may be many levels of nesting. IMPORTANT Because each statement in the trigger body must be terminated by a semicolon, you must define a different symbol to terminate the trigger body itself. In isql, include a SET TERM statement before CREATE TRIGGER to specify a terminator other than a semicolon. After the body of the trigger, include another SET TERM to change the terminator back to a semicolon. A trigger is associated with a table. The table owner and any user granted privileges to the table automatically have rights to execute associated triggers. 82
CREATE TRIGGER Triggers can be granted privileges on tables, just as users or procedures can be granted privileges. Use the GRANT statement, but instead of using TO username, use TO TRIGGER trigger_name. Triggers’ privileges can be revoked similarly using REVOKE. When a user performs an action that fires a trigger, the trigger will have privileges to perform its actions if one of the following conditions is true: g The trigger has privileges for the action. g The user has privileges for the action. Firebird procedure and trigger language is a complete programming language for stored procedures and triggers. It includes: g SQL data manipulation statements: INSERT, UPDATE, DELETE, and singleton SELECT. g SQL operators and expressions, including generators and UDFs that are linked with the calling application. g Powerful extensions to SQL, including assignment statements, control-flow statements, context variables, event-posting statements, exceptions, and error-handling statements. LANGUAGE REFERENCE 83
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE The following table summarizes language extensions for triggers. For a complete description of each statement, see Chapter 3, “Procedures and Triggers.” Statement Description BEGIN … END Defines a block of statements that executes as one • The BEGIN keyword starts the block; the END keyword terminates it • Neither should be followed by a semicolon variable = expression Assignment statement that assigns the value of expression to variable, a local variable, input parameter, or output parameter /* comment_text */ Programmer’s comment, where comment_text can be any number of lines of text EXCEPTION exception_name Raises the named exception; an exception is a user-defined error that returns an error message to the calling application unless handled by a WHEN statement EXECUTE PROCEDURE Executes stored procedure, proc_name, with the listed proc_name [var [, var …]] input arguments [RETURNING_VALUES • Returns values in the listed output arguments following var [, var …]] RETURNING_VALUES • Input and output arguments must be local variables. EXIT Jumps to the final END statement in the procedure FOR select_statement Repeats the statement or block following DO for every DO compound_statement qualifying row retrieved by select_statement select_statement A normal SELECT statement, except that the INTO clause is required and must come last compound_statement Either a single statement in procedure and trigger language or a block of statements bracketed by BEGIN and END IF (condition) Tests condition, and if it is TRUE, performs the statement or THEN compound_statement block following THEN; otherwise, performs the statement or [ELSE compound_statement] block following ELSE, if present TABLE 2.8 Procedure and trigger language extensions 84
CREATE TRIGGER Statement Description condition A Boolean expression (TRUE, FALSE, or UNKNOWN), generally two expressions as operands of a comparison operator NEW.column New context variable that indicates a new column value in an INSERT or UPDATE operation OLD.column Old context variable that indicates a column value before an UPDATE or DELETE operation POST_EVENT event_name | col Posts the event, event_name, or uses the value in col as an event name WHILE (condition) While condition is TRUE, keep performing DO compound_statement compound_statement • Tests condition, andperforms compound_statement if condition is TRUE • Repeats this sequence until condition is no longer TRUE WHEN {error [, error …] | ANY} Error-handling statement. When one of the specified errors DO compound_statement occurs, performs compound_statement. WHEN statements, if present, must come at the end of a block, just before END • ANY: Handles any errors error EXCEPTION exception_name, SQLCODE errcode or GDSCODE number TABLE 2.8 Procedure and trigger language extensions (continued) Examples The following trigger, SAVE_SALARY_CHANGE, makes correlated updates to the SALARY_HISTORY table when a change is made to an employee’s salary in the EMPLOYEE table: SET TERM !! ; CREATE TRIGGER SAVE_SALARY_CHANGE FOR EMPLOYEE AFTER UPDATE AS BEGIN IF (OLD.SALARY <> NEW.SALARY) THEN INSERT INTO SALARY_HISTORY (EMP_NO, CHANGE_DATE, UPDATER_ID, OLD_SALARY, PERCENT_CHANGE) VALUES (OLD.EMP_NO, ’now’, USER,OLD.SALARY, (NEW.SALARY - OLD.SALARY) * 100 / OLD.SALARY); END !! SET TERM ; !! LANGUAGE REFERENCE 85
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE The following trigger, SET_CUST_NO, uses a generator to create unique customer numbers when a new customer record is inserted in the CUSTOMER table: SET TERM !! ; CREATE TRIGGER SET_CUST_NO FOR CUSTOMER BEFORE INSERT AS BEGIN NEW.CUST_NO = GEN_ID(CUST_NO_GEN, 1); END !! SET TERM ; !! The following trigger, POST_NEW_ORDER, posts an event named “new_order” whenever a new record is inserted in the SALES table: SET TERM !! ; CREATE TRIGGER POST_NEW_ORDER FOR SALES AFTER INSERT AS BEGIN POST_EVENT ’new_order’; END !! SET TERM ; !! The following four fragments of trigger headers demonstrate how the POSITION option determines trigger firing order: CREATE TRIGGER A FOR accounts BEFORE UPDATE POSITION 5 … /*Trigger body follows*/ CREATE TRIGGER B FOR accounts BEFORE UPDATE POSITION 0 … /*Trigger body follows*/ CREATE TRIGGER C FOR accounts AFTER UPDATE POSITION 5 … /*Trigger body follows*/ CREATE TRIGGER D FOR accounts AFTER UPDATE POSITION 3 … /*Trigger body follows*/ When this update takes place: UPDATE accounts SET account_status = 'on_hold' WHERE account_balance <0; The triggers fire in this order: 86
CREATE VIEW 1. Trigger B fires. 2. Trigger A fires. 3. The update occurs. 4. Trigger D fires. 5. Trigger C fires. See Also ALTER EXCEPTION, ALTER TRIGGER, CREATE EXCEPTION, CREATE PROCEDURE, DROP EXCEPTION, DROP TRIGGER, EXECUTE PROCEDURE For more information on creating and using triggers, see the Data Definition Guide. For a complete description of the statements in procedure and trigger language, see Chapter 3, “Procedures and Triggers.” CREATE VIEW Creates a new view of data from one or more tables. Available in SQL, DSQL, and isql. Syntax CREATE VIEW name [(view_col [, view_col …])] AS <select> [WITH CHECK OPTION]; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name for the view; must be unique among all view, table, and procedure names in the database view_col Names the columns for the view • Column names must be unique among all column names in the view• Required if the view includes columns based on expressions; otherwise optional • Default: Column name from the underlying table select Specifies the selection criteria for rows to be included in the view WITH CHECK OPTION Prevents INSERT or UPDATE operations on an updatable view if the INSERT or UPDATE violates the search condition specified in the WHERE clause of the view’s SELECT clause LANGUAGE REFERENCE 87
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Description CREATE VIEW describes a view of data based on one or more underlying tables in the database. The rows to return are defined by a SELECT statement that lists columns from the source tables. Only the view definition is stored in the database; a view does not directly represent physically stored data. It is possible to perform select, project, join, and union operations on views as if they were tables. The user who creates a view is its owner and has all privileges for it, including the ability to GRANT privileges to other users, roles, triggers, views, and stored procedures. A user may have privileges to a view without having access to its base tables. When creating views: g A read-only view requires SELECT privileges for any underlying tables. g An updatable view requires ALL privileges to the underlying tables. The view_col option ensures that the view always contains the same columns and that the columns always have the same view-defined names. View column names correspond in order and number to the columns listed in the SELECT clause, so specify all view column names or none. A view_col definition can contain one or more columns based on an expression that combines the outcome of two columns. The expression must return a single value, and cannot return an array or array element. If the view includes an expression, the view-column option is required. Note Any columns used in the value expression must exist before the expression can be defined. A SELECT statement clause cannot include the ORDER BY clause. When SELECT * is used rather than a column list, order of display is based on the order in which columns are stored in the base table. WITH CHECK OPTION enables Firebird to verify that a row added to or updated in a view is able to be seen through the view before allowing the operation to succeed. Do not use WITH CHECK OPTION for read-only views. Note You cannot select from a view that is based on the result set of a stored procedure. Note DSQL does not support view definitions containing UNION clauses. To create such a view, use embedded SQL. A view is updatable if: g It is a subset of a single table or another updatable view. g All base table columns excluded from the view definition allow NULL values. g The view’s SELECT statement does not contain subqueries, a DISTINCT predicate, a HAVING clause, aggregate functions, joined tables, user-defined functions, or stored procedures. 88
CREATE VIEW If the view definition does not meet these conditions, it is considered read-only. Note Read-only views can be updated by using a combination of user-defined referential constraints, triggers, and unique indexes. Examples The following isql statement creates an updatable view: CREATE VIEW SNOW_LINE (CITY, STATE, SNOW_ALTITUDE) AS SELECT CITY, STATE, ALTITUDE FROM CITIES WHERE ALTITUDE > 5000; The next isql statement uses a nested query to create a view: CREATE VIEW RECENT_CITIES AS SELECT STATE, CITY, POPULATION FROM CITIES WHERE STATE IN (SELECT STATE FROM STATES WHERE STATEHOOD > ’1-JAN-1850’); In an updatable view, the WITH CHECK OPTION prevents any inserts or updates through the view that do not satisfy the WHERE clause of the CREATE VIEW SELECT statement: CREATE VIEW HALF_MILE_CITIES AS SELECT CITY, STATE, ALTITUDE FROM CITIES WHERE ALTITUDE > 2500 WITH CHECK OPTION; The WITH CHECK OPTION clause in the view would prevent the following insertion: INSERT INTO HALF_MILE_CITIES (CITY, STATE, ALTITUDE) VALUES (’Chicago’, ’Illinois’, 250); On the other hand, the following UPDATE would be permitted: INSERT INTO HALF_MILE_CITIES (CITY, STATE, ALTITUDE) VALUES (’Truckee’, ’California’, 2736); The WITH CHECK OPTION clause does not allow updates through the view which change the value of a row so that the view cannot retrieve it. For example, the WITH CHECK OPTION in the HALF_MILE_CITIES view prevents the following update: UPDATE HALF_MILE_CITIES SET ALTITUDE = 2000 WHERE STATE = ’NY’; The next isql statement creates a view that joins two tables, and so is read-only: CREATE VIEW PHONE_LIST AS SELECT EMP_NO, FIRST_NAME, LAST_NAME, PHONE_EXT, LOCATION, PHONE_NO LANGUAGE REFERENCE 89
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE FROM EMPLOYEE, DEPARTMENT WHERE EMPLOYEE.DEPT_NO = DEPARTMENT.DEPT_NO; See Also CREATE TABLE, DROP VIEW, GRANT, INSERT, REVOKE, SELECT, UPDATE For a complete discussion of views, see the Data Definition Guide. DECLARE CURSOR Defines a cursor for a table by associating a name with the set of rows specified in a SELECT statement. Available in SQL and DSQL. Syntax SQL form: DECLARE cursor CURSOR FOR <select> [FOR UPDATE OF <col> [, <col>…]]; DSQL form: DECLARE cursor CURSOR FOR <statement_id> Blob form: See DECLARE CURSOR (BLOB) Argument Description cursor Name for the cursor select Determines which rows to retrieve. SQL only FOR UPDATE OF col [, col …] Enables UPDATE and DELETE of specified column for retrieved rows statement_id SQL statement name of a previously prepared statement, which in this case must be a SELECT statement. DSQL only Description DECLARE CURSOR defines the set of rows that can be retrieved using the cursor it names. It is the first member of a group of table cursor statements that must be used in sequence. select specifies a SELECT statement that determines which rows to retrieve. The SELECT statement cannot include INTO or ORDER BY clauses. The FOR UPDATE OF clause is necessary for updating or deleting rows using the WHERE CURRENT OF clause with UPDATE and DELETE. 90
DECLARE CURSOR A cursor is a one-way pointer into the ordered set of rows retrieved by the select expression in the DECLARE CURSOR statement. It enables sequential access to retrieved rows in turn. There are four related cursor statements: Stage Statement Purpose 1 DECLARE CURSOR Declares the cursor; the SELECT statement determines rows retrieved for the cursor 2 OPEN Retrieves the rows specified for retrieval with DECLARE CURSOR; the resulting rows become the cursor’s active set 3 FETCH Retrieves the current row from the active set, starting with the first row; subsequent FETCH statements advance the cursor through the set 4 CLOSE Closes the cursor and releases system resources Examples The following embedded SQL statement declares a cursor with a search condition: EXEC SQL DECLARE C CURSOR FOR SELECT CUST_NO, ORDER_STATUS FROM SALES WHERE ORDER_STATUS IN (’open’, ’shipping’); The next DSQL statement declares a cursor for a previously prepared statement, QUERY1: DECLARE Q CURSOR FOR QUERY1 See Also CLOSE, DECLARE CURSOR (BLOB), FETCH, OPEN, PREPARE, SELECT LANGUAGE REFERENCE 91
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DECLARE CURSOR (BLOB) Declares a Blob cursor for read or insert. Available in SQL. Syntax DECLARE cursor CURSOR FOR {READ BLOB column FROM table | INSERT BLOB column INTO table} [FILTER [FROM subtype] TO subtype] [MAXIMUM_SEGMENT length]; Argument Description cursor Name for the Blob cursor column Name of the Blob column table Table name READ BLOB Declares a read operation on the Blob INSERT BLOB Declares a write operation on the Blob [FILTER [FROM Specifies optional Blob filters used to translate a Blob from one subtype] TO subtype] user-specified format to another; subtype determines which filters are used for translation MAXIMUM_ Length of the local variable to receive the Blob data after a FETCH SEGMENT length operation Description Declares a cursor for reading or inserting Blob data. A Blob cursor can be associated with only one Blob column. To read partial Blob segments when a host-language variable is smaller than the segment length of a Blob, declare the Blob cursor with the MAXIMUM_SEGMENT clause. If length is less than the Blob segment, FETCH returns length bytes. If the same or greater, it returns a full segment (the default). Examples The following embedded SQL statement declares a READ BLOB cursor and uses the MAXIMUM_SEGMENT option: EXEC SQL DECLARE BC CURSOR FOR READ BLOB JOB_REQUIREMENT FROM JOB MAXIMUM_SEGMENT 40; 92
DECLARE EXTERNAL FUNCTION The next embedded SQL statement declares an INSERT BLOB cursor: EXEC SQL DECLARE BC CURSOR FOR INSERT BLOB JOB_REQUIREMENt INTO JOB; See Also CLOSE (BLOB), FETCH (BLOB), INSERT CURSOR (BLOB), OPEN (BLOB) DECLARE EXTERNAL FUNCTION Declares an existing user-defined function (UDF) to a database. Available in SQL, DSQL, and isql. Syntax DECLARE EXTERNAL FUNCTION name [datatype | CSTRING (int) [, datatype | CSTRING (int) …]] RETURNS {datatype [BY VALUE] | CSTRING (int)} [FREE_IT] ENTRY_POINT 'entryname' MODULE_NAME 'modulename'; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Note Whenever a UDF returns a value by reference to dynamically allocated memory, you must declare it using the FREE_IT keyword in order to free the allocated memory. Argument Description name Name of the UDF to use in SQL statements; can be different from the name of the function specified after the ENTRY_POINT keyword datatype Datatype of an input or return parameter • All input parameters are passed to a UDF by reference• Return parameters can be passed by value• Cannot be an array element CSTRING (int) Specifies a UDF that returns a null-terminated string int bytes in length RETURNS Specifies the return value of a function BY VALUE Specifies that a return value should be passed by value rather than by reference LANGUAGE REFERENCE 93
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description FREE_IT Frees memory of the return value after the UDF finishes running • Use only if the memory is allocated dynamically in the UDF • See also Language Reference, Chapter 5 'entryname' Quoted string specifying the name of the UDF in the source code as stored in the UDF library 'modulename' Quoted file name identifying the library that contains the UDF; the placement of the library in the file system must meet one of the following criteria: • The library is in ib_install_dir/UDF • The library in a directory other than ib_install_dir/UDF and the complete pathname to the directory, including a drive letter in the case of a Windows server, is listed in the Firebird configuration file. • See the UDF chapter of the Developer’s Guide for more about how Firebird finds the library Description DECLARE EXTERNAL FUNCTION provides information about a UDF to a database: where to find it, its name, the input parameters it requires, and the single value it returns. Each UDF in a library must be declared once to each database where it will be used. As long as the entry point and module name do not change, there is no need to redelcare a UDF, even if the function itself is modified. entryname is the actual name of the function as stored in the UDF library. It does not have to match the name of the UDF as stored in the database. The module name does not need to include a path. However, the module must either be placed in ib_install_dir/UDF or must be listed in the Firebird configuration file. To specify a location for UDF libraries in a configuration file, enter a line of the following form for Windows platforms: EXTERNAL_FUNCTION_DIRECTORY D:\Mylibraries\Firebird For UNIX , the line does not include a drive letter: EXTERNAL_FUNCTION_DIRECTORY \Mylibraries\Firebird Note that beginning with Firebird 6, it is no longer sufficient to include a complete path name for the module in the DECLARE EXTERNAL FUNCTION statement. You must list the path in the Firebird configuration file if it is other than ib_install_dir/UDF. A path name is no longer useful in the DECLARE EXTERNAL FUNCTION statement. The Firebird configuration file is called ibconfig on Windows machines, isc_config on UNIX machines. 94
DECLARE FILTER FOR NETWARE SERVERS Beginning with Firebird 5.6, the UDF library is statically linked to NetWare servers so that the UDFs are available as external functions. To make them available to a database on a Netware server, follow htese steps: 1. On a Windows client, connect to the database where you need the functions. 2. Run the ib_udf.sql script that is located in the ib_install_dir/Examples/UDF directory (Firebird 6 and later) or Examples/API directory (Firebird 5.6) using ISQL with the -i switch: Examples The following isql statement declares the TOPS() UDF to a database: DECLARE EXTERNAL FUNCTION TOPS CHAR(256), INTEGER, BLOB RETURNS INTEGER BY VALUE ENTRY_POINT ’te1’ MODULE_NAME ’tm1.dll’; This example does not need the FREE_IT keyword because only cstrings, CHAR, and VARCHAR return types require memory allocation. The next example declares the LOWERS() UDF and frees the memory allocated for the return value: DECLARE EXTERNAL FUNCTION LOWERS VARCHAR(256) RETURNS CSTRING(256) FREE_IT ENTRY POINT ’fn_lower’ MODULE_NAME ’udflib.dll’; See Also DROP EXTERNAL FUNCTION For more information about writing UDFs, see “Working with UDFs” in the Developer’s Guide. DECLARE FILTER Declares an existing Blob filter to a database. Available in SQL, DSQL, and isql. Syntax DECLARE FILTER filter INPUT_TYPE subtype OUTPUT_TYPE subtype ENTRY_POINT ’entryname’ MODULE_NAME ’modulename’; LANGUAGE REFERENCE 95
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description filter Name of the filter; must be unique among filter names in the database INPUT_TYPE subtype Specifies the Blob subtype from which data is to be converted OUTPUT_TYPE subtype Specifies the Blob subtype into which data is to be converted ‘entryname’ Quoted string specifying the name of the Blob filter as stored in a linked library ‘modulename’ Quoted file specification identifying the object module in which the filter is stored Description DECLARE FILTER provides information about an existing Blob filter to the database: where to find it, its name, and the Blob subtypes it works with. A Blob filter is a user-written program that converts data stored in Blob columns from one subtype to another. INPUT_TYPE and OUTPUT_TYPE together determine the behavior of the Blob filter. Each filter declared to the database should have a unique combination of INPUT_TYPE and OUTPUT_TYPE integer values. Firebird provides a built-in type of 1, for handling text. User-defined types must be expressed as negative values. entryname is the name of the Blob filter stored in the library. When an application uses a Blob filter, it calls the filter function with this name. Example The following isql statement declares a Blob filter: DECLARE FILTER DESC_FILTER INPUT_TYPE 1 OUTPUT_TYPE -4 ENTRY_POINT ’desc_filter’ MODULE_NAME ’FILTERLIB’; See Also DROP FILTER For instructions on writing Blob filters, see the Embedded SQL Guide. For more information about Blob subtypes, see the Data Definition Guide. 96
DECLARE STATEMENT DECLARE STATEMENT Identifies dynamic SQL statements before they are prepared and executed in an embedded program. Available in SQL. Syntax DECLARE <statement> STATEMENT; Argument Description statement Name of an SQL variable for a user-supplied SQL statement to prepare and execute at runtime Description DECLARE STATEMENT names an SQL variable for a user-supplied SQL statement to prepare and execute at run time. DECLARE STATEMENT is not executed, so it does not produce run-time errors. The statement provides internal documentation. Example The following embedded SQL statement declares Q1 to be the name of a string for preparation and execution. EXEC SQL DECLARE Q1 STATEMENT; See Also EXECUTE, EXECUTE IMMEDIATE, PREPARE DECLARE TABLE Describes the structure of a table to the preprocessor, gpre, before it is created with CREATE TABLE. Available in SQL. Syntax DECLARE table TABLE (<table_def>); Argument Description table Name of the table; table names must be unique within the database table_def Definition of the table; for complete table definition syntax, see CREATE TABLE Description DECLARE TABLE causes gpre to store a table description. You must use it if you both create and populate a table with data in the same program. If the declared table already exists in the database or if the declaration contains syntax errors, gpre returns an error. LANGUAGE REFERENCE 97
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE When a table is referenced at run time, the column descriptions and datatypes are checked against the description stored in the database. If the table description is not in the database and the table is not declared, or if column descriptions and datatypes do not match, the application returns an error. DECLARE TABLE can include an existing domain in a column definition, but must give the complete column description if the domain is not defined at compile time. DECLARE TABLE cannot include integrity constraints and column attributes, even if they are present in a subsequent CREATE TABLE statement. IMPORTANT DECLARE TABLE cannot appear in a program that accesses multiple databases. Example The following embedded SQL statements declare and create a table: EXEC SQL DECLARE STOCK TABLE (MODEL SMALLINT, MODELNAME CHAR(10), ITEMID INTEGER); EXEC SQL CREATE TABLE STOCK (MODEL SMALLINT NOT NULL UNIQUE, MODELNAME CHAR(10) NOT NULL, ITEMID INTEGER NOT NULL, CONSTRAINT MOD_UNIQUE UNIQUE (MODELNAME, ITEMID)); See Also CREATE DOMAIN, CREATE TABLE DELETE Removes rows in a table or in the active set of a cursor. Available in SQL, DSQL, and isql. Syntax SQL and DSQL form: IMPORTANT Omit the terminating semicolon for DSQL. DELETE [TRANSACTION transaction] FROM table {[WHERE <search_condition>] | WHERE CURRENT OF cursor}; <search_condition> = Search condition as specified in SELECT. isql form: 98
DELETE DELETE FROM TABLE [WHERE <search_condition>]; Argument Description TRANSACTION Name of the transaction under control of which the statement is transaction executed; SQL only table Name of the table from which to delete rows WHERE Search condition that specifies the rows to delete; without this clause, search_condition DELETE affects all rows in the specified table or view WHERE CURRENT OF cursor Specifies that the current row in the active set of cursor is to be deleted DELETE specifies one or more rows to delete from a table or updatable view. DELETE is one of the database privileges controlled by the GRANT and REVOKE statements. The TRANSACTION clause can be used in multiple transaction SQL applications to specify which transaction controls the DELETE operation. The TRANSACTION clause is not available in DSQL or isql. For searched deletions, the optional WHERE clause can be used to restrict deletions to a subset of rows in the table. IMPORTANT Without a WHERE clause, a searched delete removes all rows from a table. When performing a positioned delete with a cursor, the WHERE CURRENT OF clause must be specified to delete one row at a time from the active set. Examples The following isql statement deletes all rows in a table: DELETE FROM EMPLOYEE_PROJECT; The next embedded SQL statement is a searched delete in an embedded application. It deletes all rows where a host-language variable equals a column value. EXEC SQL DELETE FROM SALARY_HISTORY WHERE EMP_NO = :emp_num; The following embedded SQL statements use a cursor and the WHERE CURRENT OF option to delete rows from CITIES with a population less than the host variable, min_pop. They declare and open a cursor that finds qualifying cities, fetch rows into the cursor, and delete the current row pointed to by the cursor. EXEC SQL DECLARE SMALL_CITIES CURSOR FOR SELECT CITY, STATE LANGUAGE REFERENCE 99
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE FROM CITIES WHERE POPULATION < :min_pop; EXEC SQL OPEN SMALL_CITIES; EXEC SQL FETCH SMALL_CITIES INTO :cityname, :statecode; WHILE (!SQLCODE) {EXEC SQL DELETE FROM CITIES WHERE CURRENT OF SMALL_CITIES; EXEC SQL FETCH SMALL_CITIES INTO :cityname, :statecode;} EXEC SQL CLOSE SMALL_CITIES; See Also DECLARE CURSOR, FETCH, GRANT, OPEN, REVOKE, SELECT For more information about using cursors, see the Embedded SQL Guide. DESCRIBE Provides information about columns that are retrieved by a dynamic SQL (DSQL) statement, or information about dynamic parameters that statement passes. Available in SQL. Syntax DESCRIBE [OUTPUT | INPUT] statement {INTO | USING} SQL DESCRIPTOR xsqlda; Argument Description OUTPUT [Default] Indicates that column information should be returned in the XSQLDA INPUT Indicates that dynamic parameter information should be stored in the XSQLDA statement A previously defined alias for the statement to DESCRIBE. • Use PREPARE to define aliases {INTO | USING} SQL DESCRIPTOR xsqlda Specifies the XSQLDA to use for the DESCRIBE statement Description DESCRIBE has two uses: 100
DESCRIBE g As a describe output statement, DESCRIBE stores into an XSQLDA a description of the columns that make up the select list of a previously prepared statement. If the PREPARE statement included an INTO clause, it is unnecessary to use DESCRIBE as an output statement. g As a describe input statement, DESCRIBE stores into an XSQLDA a description of the dynamic parameters that are in a previously prepared statement. DESCRIBE is one of a group of statements that process DSQL statements. Statement Purpose PREPARE Readies a DSQL statement for execution DESCRIBE Fills in the XSQLDA with information about the statement EXECUTE Executes a previously prepared statement EXECUTE IMMEDIATE Prepares a DSQL statement, executes it once, and discards it Separate DESCRIBE statements must be issued for input and output operations. The INPUT keyword must be used to store dynamic parameter information. IMPORTANT When using DESCRIBE for output, if the value returned in the sqld field in the XSQLDA is larger than the sqln field, you must: g Allocate more storage space for XSQLVAR structures. g Reissue the DESCRIBE statement. Note The same XSQLDA structure can be used for input and output if desired. Example The following embedded SQL statement retrieves information about the output of a SELECT statement: EXEC SQL DESCRIBE Q INTO xsqlda The next embedded SQL statement stores information about the dynamic parameters passed with a statement to be executed: EXEC SQL DESCRIBE INPUT Q2 USING SQL DESCRIPTOR xsqlda; See Also EXECUTE, EXECUTE IMMEDIATE, PREPARE For more information about DSQL programming and the XSQLDA, see the Embedded SQL Guide. LANGUAGE REFERENCE 101
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DISCONNECT Detaches an application from a database. Available in SQL. Syntax DISCONNECT {{ALL | DEFAULT} | dbhandle [, dbhandle] …]}; Argument Description ALL|DEFAULT Either keyword detaches all open databases dbhandle Previously declared database handle specifying a database to detach Description DISCONNECT closes a specific database identified by a database handle or all databases, releases resources used by the attached database, zeroes database handles, commits the default transaction if the gpre -manual option is not in effect, and returns an error if any non-default transaction is not committed. Before using DISCONNECT, commit or roll back the transactions affecting the database to be detached. To reattach to a database closed with DISCONNECT, reopen it with a CONNECT statement. Examples The following embedded SQL statements close all databases: EXEC SQL DISCONNECT DEFAULT; EXEC SQL DISCONNECT ALL; The next embedded SQL statements close the databases identified by their handles: EXEC SQL DISCONNECT DB1; EXEC SQL DISCONNECT DB1, DB2; See Also COMMIT, CONNECT, ROLLBACK, SET DATABASE DROP DATABASE Deletes the currently attached database. Available in isql. Syntax DROP DATABASE; 102
DROP DOMAIN Description DROP DATABASE deletes the currently attached database, including any associated secondary, shadow, and log files. Dropping a database deletes any data it contains. A database can be dropped by its creator, the SYSDBA user, and any users with operating system root privileges. Example The following isql statement deletes the current database: DROP DATABASE; See Also ALTER DATABASE, CREATE DATABASE DROP DOMAIN Deletes a domain from a database. Available in SQL, DSQL, and isql. Syntax DROP DOMAIN name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing domain Description DROP DOMAIN removes an existing domain definition from a database. If a domain is currently used in any column definition in the database, the DROP operation fails. To prevent failure, use ALTER TABLE to delete the columns based on the domain before executing DROP DOMAIN. A domain may be dropped by its creator, the SYSDBA, and any users with operating system root privileges. Example The following isql statement deletes a domain: DROP DOMAIN COUNTRYNAME; See Also ALTER DOMAIN, ALTER TABLE, CREATE DOMAIN LANGUAGE REFERENCE 103
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DROP EXCEPTION Deletes an exception from a database. Available in DSQL and isql. Syntax DROP EXCEPTION name Argument Description name Name of an existing exception message Description DROP EXCEPTION removes an exception from a database. Exceptions used in existing procedures and triggers cannot be dropped. Tip In isql, SHOW EXCEPTION displays a list of exceptions’ dependencies, the procedures and triggers that use the exceptions. An exception can be dropped by its creator, the SYSDBA user, and any user with operating system root privileges. Example This isql statement drops an exception: DROP EXCEPTION UNKNOWN_EMP_ID; See Also ALTER EXCEPTION, ALTER PROCEDURE, ALTER TRIGGER, CREATE EXCEPTION, CREATE PROCEDURE, CREATE TRIGGER 104
DROP EXTERNAL FUNCTION DROP EXTERNAL FUNCTION Removes a user-defined function (UDF) declaration from a database. Available in SQL, DSQL, and isql. Syntax DROP EXTERNAL FUNCTION name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing UDF Description DROP EXTERNAL FUNCTION deletes a UDF declaration from a database. Dropping a UDF declaration from a database does not remove it from the corresponding UDF library, but it does make the UDF inaccessible from the database. Once the definition is dropped, any applications that depend on the UDF will return run-time errors. A UDF can be dropped by its declarer, the SYSDBA user, or any users with operating system root privileges. Example This isql statement drops a UDF: DROP EXTERNAL FUNCTION TOPS; See Also DECLARE EXTERNAL FUNCTION LANGUAGE REFERENCE 105
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DROP FILTER Removes a Blob filter declaration from a database. Available in SQL, DSQL, and isql. Syntax DROP FILTER name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing Blob filter Description DROP FILTER removes a Blob filter declaration from a database. Dropping a Blob filter declaration from a database does not remove it from the corresponding Blob filter library, but it does make the filter inaccessible from the database. Once the definition is dropped, any applications that depend on the filter will return run-time errors. DROP FILTER fails and returns an error if any processes are using the filter. A filter can be dropped by its creator, the SYSDBA user, or any user with operating system root privileges. IMPORTANT Example This isql statement drops a Blob filter: DROP FILTER DESC_FILTER; See Also DECLARE FILTER 106
DROP INDEX DROP INDEX Removes an index from a database. Available in SQL, DSQL, and isql. Syntax DROP INDEX name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing index Description DROP INDEX removes a user-defined index from a database. An index can be dropped by its creator, the SYSDBA user, or any user with operating system root privileges. IMPORTANT You cannot drop system-defined indexes, such as those for UNIQUE, PRIMARY KEY, and FOREIGN KEY. An index in use is not dropped until it is no longer in use. Example The following isql statement deletes an index: DROP INDEX MINSALX; See Also ALTER INDEX, CREATE INDEX For more information about integrity constraints and system-defined indexes, see the Data Definition Guide. LANGUAGE REFERENCE 107
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DROP PROCEDURE Deletes an existing stored procedure from a database. Available in DSQL, and isql. Syntax DROP PROCEDURE name Argument Description name Name of an existing stored procedure Description DROP PROCEDURE removes an existing stored procedure definition from a database. Procedures used by other procedures, triggers, or views cannot be dropped. Procedures currently in use cannot be dropped. Tip In isql, SHOW PROCEDURE displays a list of procedures’ dependencies, the procedures, triggers, exceptions, and tables that use the procedures. A procedure can be dropped by its creator, the SYSDBA user, or any user with operating system root privileges. Example The following isql statement deletes a procedure: DROP PROCEDURE GET_EMP_PROJ; See Also ALTER PROCEDURE, CREATE PROCEDURE, EXECUTE PROCEDURE DROP ROLE Deletes a role from a database. Available in SQL, DSQL, and isql. Syntax DROP ROLE rolename; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description rolename Name of an existing role Description DROP ROLE deletes a role that was previously created using CREATE ROLE. Any privileges that users acquired or granted through their membership in the role are revoked. 108
DROP SHADOW A role can be dropped by its creator, the SYSDBA user, or any user with superuser privileges. Example The following isql statement deletes a role from its database: DROP ROLE administrator; See Also CREATE ROLE, GRANT, REVOKE DROP SHADOW Deletes a shadow from a database. Available in SQL, DSQL, and isql. Syntax DROP SHADOW set_num; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description set_num Positive integer to identify an existing shadow set Description DROP SHADOW deletes a shadow set and detaches from the shadowing process. The isql SHOW DATABASE command can be used to see shadow set numbers for a database. A shadow can be dropped by its creator, the SYSDBA user, or any user with operating system root privileges. Example The following isql statement deletes a shadow set from its database: DROP SHADOW 1; See Also CREATE SHADOW LANGUAGE REFERENCE 109
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DROP TABLE Removes a table from a database. Available in SQL, DSQL, and isql. Syntax DROP TABLE name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing table Description DROP TABLE removes a table’s data, metadata, and indexes from a database. It also drops any triggers that reference the table. A table referenced in an SQL expression, a view, integrity constraint, or stored procedure cannot be dropped. A table used by an active transaction is not dropped until it is free. Note When used to drop an external table, DROP TABLE only removes the table definition from the database. The external file is not deleted. A table can be dropped by its creator, the SYSDBA user, or any user with operating system root privileges. Example The following embedded SQL statement drops a table: EXEC SQL DROP TABLE COUNTRY; See Also ALTER TABLE, CREATE TABLE 110
DROP TRIGGER DROP TRIGGER Deletes an existing user-defined trigger from a database. Available in DSQL and isql. Syntax DROP TRIGGER name Argument Description name Name of an existing trigger Description DROP TRIGGER removes a user-defined trigger definition from the database. System-defined triggers, such as those created for CHECK constraints, cannot be dropped. Use ALTER TABLE to drop the CHECK clause that defines the trigger. Triggers used by an active transaction cannot be dropped until the transaction is terminated. A trigger can be dropped by its creator, the SYSDBA user, or any user with operating system root privileges. Tip To inactivate a trigger temporarily, use ALTER TRIGGER and specify INACTIVE in the header. Example The following isql statement drops a trigger: DROP TRIGGER POST_NEW_ORDER; See Also ALTER TRIGGER, CREATE TRIGGER LANGUAGE REFERENCE 111
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DROP VIEW Removes a view definition from the database. Available in SQL, DSQL, and isql. Syntax DROP VIEW name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing view definition to drop Description DROP VIEW enables a view’s creator to remove a view definition from the database if the view is not used in another view, stored procedure, or CHECK constraint definition. A view can be dropped by its creator, the SYSDBA user, or any user with operating system root privileges. Example The following isql statement removes a view definition: DROP VIEW PHONE_LIST; See Also CREATE VIEW END DECLARE SECTION Identifies the end of a host-language variable declaration section. Available in SQL. Syntax END DECLARE SECTION; Description END DECLARE SECTION is used in embedded SQL applications to identify the end of host-language variable declarations for variables used in subsequent SQL statements. Example The following embedded SQL statements declare a section, and single host-language variable: EXEC SQL BEGIN DECLARE SECTION; BASED_ON EMPLOYEE.SALARY salary; EXEC SQL END DECLARE SECTION; See Also BASED ON, BEGIN DECLARE SECTION 112
EVENT INIT EVENT INIT Registers interest in one or more events with the Firebird event manager. Available in SQL. Syntax EVENT INIT request_name [dbhandle] [(’string’ | :variable [, ’string’ | :variable …]); Argument Description request_name Application event handle dbhandle Specifies the database to examine for occurrences of the events; if omitted, dbhandle defaults to the database named in the most recent SET DATABASE statement ‘string’ Unique name identifying an event associated with event_name :variable Host-language character array containing a list of event names to associate with Description EVENT INIT is the first step in the Firebird two-part synchronous event mechanism: 1. EVENT INIT registers an application’s interest in an event. 2. EVENT WAIT causes the application to wait until notified of the event’s occurrence. EVENT INIT registers an application’s interest in a list of events in parentheses. The list should correspond to events posted by stored procedures or triggers in the database. If an application registers interest in multiple events with a single EVENT INIT, then when one of those events occurs, the application must determine which event occurred. Events are posted by a POST_EVENT call within a stored procedure or trigger. The event manager keeps track of events of interest. At commit time, when an event occurs, the event manager notifies interested applications. Example The following embedded SQL statement registers interest in an event: EXEC SQL EVENT INIT ORDER_WAIT EMPDB (’new_order’); See Also CREATE PROCEDURE, CREATE TRIGGER, EVENT WAIT, SET DATABASE For more information about events, see the Embedded SQL Guide. LANGUAGE REFERENCE 113
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE EVENT WAIT Causes an application to wait until notified of an event’s occurrence. Available in SQL. Syntax EVENT WAIT request_name; Argument Description request_name Application event handle declared in a previous EVENT INIT statement Description EVENT WAIT is the second step in the Firebird two-part synchronous event mechanism. After a program registers interest in an event, EVENT WAIT causes the process running the application to sleep until the event of interest occurs. Examples The following embedded SQL statements register an application event name and indicate the program is ready to receive notification when the event occurs: EXEC SQL EVENT INIT ORDER_WAIT EMPDB (’new_order’); EXEC SQL EVENT WAIT ORDER_WAIT; See Also EVENT INIT For more information about events, see the Embedded SQL Guide. 114
EXECUTE EXECUTE Executes a previously prepared dynamic SQL (DSQL) statement. Available in SQL. Syntax EXECUTE [TRANSACTION transaction] statement [USING SQL DESCRIPTOR xsqlda] [INTO SQL DESCRIPTOR xsqlda]; Argument Description TRANSACTION transaction Specifies the transaction under which execution occurs statement Alias of a previously prepared statement to execute USING SQL DESCRIPTOR Specifies that values corresponding to the prepared statement’s parameters should be taken from the specified XSQLDA INTO SQL DESCRIPTOR Specifies that return values from the executed statement should be stored in the specified XSQLDA xsqlda XSQLDA host-language variable Description EXECUTE carries out a previously prepared DSQL statement. It is one of a group of statements that process DSQL statements. Statement Purpose PREPARE Readies a DSQL statement for execution DESCRIBE Fills in the XSQLDA with information about the statement EXECUTE Executes a previously prepared statement EXECUTE IMMEDIATE Prepares a DSQL statement, executes it once, and discards it Before a statement can be executed, it must be prepared using the PREPARE statement. The statement can be any SQL data definition, manipulation, or transaction management statement. Once it is prepared, a statement can be executed any number of times. The TRANSACTION clause can be used in SQL applications running multiple, simultaneous transactions to specify which transaction controls the EXECUTE operation. USING DESCRIPTOR enables EXECUTE to extract a statement’s parameters from an XSQLDA structure previously loaded with values by the application. It need only be used for statements that have dynamic parameters. LANGUAGE REFERENCE 115
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE INTO DESCRIPTOR enables EXECUTE to store return values from statement execution in a specified XSQLDA structure for application retrieval. It need only be used for DSQL statements that return values. Note If an EXECUTE statement provides both a USING DESCRIPTOR clause and an INTO DESCRIPTOR clause, then two XSQLDA structures must be provided. Example The following embedded SQL statement executes a previously prepared DSQL statement: EXEC SQL EXECUTE DOUBLE_SMALL_BUDGET; The next embedded SQL statement executes a previously prepared statement with parameters stored in an XSQLDA: EXEC SQL EXECUTE Q USING DESCRIPTOR xsqlda; The following embedded SQL statement executes a previously prepared statement with parameters in one XSQLDA, and produces results stored in a second XSQLDA: EXEC SQL EXECUTE Q USING DESCRIPTOR xsqlda_1 INTO DESCRIPTOR xsqlda_2; See Also DESCRIBE, EXECUTE IMMEDIATE, PREPARE For more information about DSQL programming and the XSQLDA, see the Embedded SQL Guide. 116
EXECUTE IMMEDIATE EXECUTE IMMEDIATE Prepares a dynamic SQL (DSQL) statement, executes it once, and discards it. Available in SQL. Syntax EXECUTE IMMEDIATE [TRANSACTION transaction] {:variable | ’string’} [USING SQL DESCRIPTOR xsqlda]; Argument Description TRANSACTION transaction Specifies the transaction under which execution occurs :variable Host variable containing the SQL statement to execute ‘string’ A string literal containing the SQL statement to execute USING SQL DESCRIPTOR Specifies that values corresponding to the statement’s parameters should be taken from the specified XSQLDA xsqlda XSQLDA host-language variable Description EXECUTE IMMEDIATE prepares a DSQL statement stored in a host-language variable or in a literal string, executes it once, and discards it. To prepare and execute a DSQL statement for repeated use, use PREPARE and EXECUTE instead of EXECUTE IMMEDIATE. The TRANSACTION clause can be used in SQL applications running multiple, simultaneous transactions to specify which transaction controls the EXECUTE IMMEDIATE operation. The SQL statement to execute must be stored in a host variable or be a string literal. It can contain any SQL data definition statement or data manipulation statement that does not return output. USING DESCRIPTOR enables EXECUTE IMMEDIATE to extract the values of a statement’s parameters from an XSQLDA structure previously loaded with appropriate values. Example The following embedded SQL statement prepares and executes a statement in a host variable: EXEC SQL EXECUTE IMMEDIATE :insert_date; See Also DESCRIBE, EXECUTE IMMEDIATE, PREPARE For more information about DSQL programming and the XSQLDA, see the Embedded SQL Guide. LANGUAGE REFERENCE 117
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE EXECUTE PROCEDURE Calls a stored procedure. Available in SQL, DSQL, and isql. Syntax SQL form: EXECUTE PROCEDURE [TRANSACTION transaction] name [:param [[INDICATOR]:indicator]] [, :param [[INDICATOR]:indicator] …] [RETURNING_VALUES :param [[INDICATOR]:indicator] [, :param [[INDICATOR]:indicator] …]]; DSQL form: EXECUTE PROCEDURE name [param [, param …]] [RETURNING_VALUES param [, param …]] isql form: EXECUTE PROCEDURE name [param [, param …]] Argument Description TRANSACTION transaction Specifies the transaction under which execution occurs name Name of an existing stored procedure in the database param Input or output parameter; can be a host variable or a constant RETURNING_VALUES: param Host variable which takes the values of an output parameter [INDICATOR] :indicator Host variable for indicating NULL or unknown values Description EXECUTE PROCEDURE calls the specified stored procedure. If the procedure requires input parameters, they are passed as host-language variables or as constants. If a procedure returns output parameters to an SQL program, host variables must be supplied in the RETURNING_VALUES clause to hold the values returned. In isql, do not use the RETURN clause or specify output parameters. isql will automatically display return values. Note In DSQL, an EXECUTE PROCEDURE statement requires an input descriptor area if it has input parameters and an output descriptor area if it has output parameters. In embedded SQL, input parameters and return values may have associated indicator variables for tracking NULL values. Indicator variables are integer values that indicate unknown or NULL values of return values. 118
FETCH An indicator variable that is less than zero indicates that the parameter is unknown or NULL. An indicator variable that is zero or greater indicates that the associated parameter is known and not NULL. Examples The following embedded SQL statement demonstrates how the executable procedure, DEPT_BUDGET, is called from embedded SQL with literal parameters: EXEC SQL EXECUTE PROCEDURE DEPT_BUDGET 100 RETURNING_VALUES :sumb; The next embedded SQL statement calls the same procedure using a host variable instead of a literal as the input parameter: EXEC SQL EXECUTE PROCEDURE DEPT_BUDGET :rdno RETURNING_VALUES :sumb; See Also ALTER PROCEDURE, CREATE PROCEDURE, DROP PROCEDURE For more information about indicator variables, see the Embedded SQL Guide. FETCH Retrieves the next available row from the active set of an opened cursor. Available in SQL and DSQL. Syntax SQL form: FETCH cursor [INTO :hostvar [[INDICATOR] :indvar] [, :hostvar [[INDICATOR] :indvar] …]]; DSQL form: FETCH cursor {INTO | USING} SQL DESCRIPTOR xsqlda Blob form: See FETCH (BLOB). Argument Description cursor Name of the opened cursor from which to fetch rows :hostvar A host-language variable for holding values retrieved with the FETCH • Optional if FETCH gets rows for DELETE or UPDATE• Required if row is displayed before DELETE or UPDATE LANGUAGE REFERENCE 119
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Argument Description :indvar Indicator variable for reporting that a column contains an unknown or NULL value [INTO|USING] SQL Specifies that values should be returned in the specified XSQLDA DESCRIPTOR xsqlda XSQLDA host-language variable Description FETCH retrieves one row at a time into a program from the active set of a cursor. The first FETCH operates on the first row of the active set. Subsequent FETCH statements advance the cursor sequentially through the active set one row at a time until no more rows are found and SQLCODE is set to 100. A cursor is a one-way pointer into the ordered set of rows retrieved by the select expression in the DECLARE CURSOR statement. A cursor enables sequential access to retrieved rows. There are four related cursor statements: Stage Statement Purpose 1 DECLARE CURSOR Declare the cursor; the SELECT statement determines rows retrieved for the cursor 2 OPEN Retrieve the rows specified for retrieval with DECLARE CURSOR; the resulting rows become the cursor’s active set 3 FETCH Retrieve the current row from the active set, starting with the first row; subsequent FETCH statements advance the cursor through the set 4 CLOSE Close the cursor and release system resources The number, size, datatype, and order of columns in a FETCH must be the same as those listed in the query expression of its matching DECLARE CURSOR statement. If they are not, the wrong values can be assigned. Examples The following embedded SQL statement fetches a column from the active set of a cursor: EXEC SQL FETCH PROJ_CNT INTO :department, :hcnt; See Also CLOSE, DECLARE CURSOR, DELETE, FETCH (BLOB), OPEN For more information about cursors and XSQLDA, see the Embedded SQL Guide. 120
FETCH (BLOB) FETCH (BLOB) Retrieves the next available segment of a Blob column and places it in the specified local buffer. Available in SQL. Syntax FETCH cursor INTO [:<buffer> [[INDICATOR] :segment_length]; Argument Description cursor Name of an open Blob cursor from which to retrieve segments :buffer Host-language variable for holding segments fetched from the Blob column; user must declare the buffer before fetching segments into it INDICATOR Optional keyword indicating that a host-language variable for indicating the number of bytes returned by the FETCH follows :segment_length Host-language variable used to indicate he number of bytes returned by the FETCH Description FETCH retrieves the next segment from a Blob and places it into the specified buffer. The host variable, segment_length, indicates the number of bytes fetched. This is useful when the number of bytes fetched is smaller than the host variable, for example, when fetching the last portion of a Blob. FETCH can return two SQLCODE values: g SQLCODE = 100 indicates that there are no more Blob segments to retrieve. g SQLCODE = 101 indicates that a partial segment was retrieved and placed in the local buffer variable. Note To ensure that a host variable buffer is large enough to hold a Blob segment buffer during FETCH operations, use the SEGMENT option of the BASED ON statement. To ensure that a host variable buffer is large enough to hold a Blob segment buffer during FETCH operations, use the SEGMENT option of the BASED ON statement. Example The following code, from an embedded SQL application, performs a BLOB FETCH: while (SQLCODE != 100) { EXEC SQL OPEN BLOB_CUR USING :blob_id; EXEC SQL LANGUAGE REFERENCE 121
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE FETCH BLOB_CUR INTO :blob_segment :blob_seg_len; while (SQLCODE !=100 || SQLCODE == 101) { blob_segment{blob_seg_len + 1] = ’\0’; printf("%*.*s",blob_seg_len,blob_seg_len,blob_segment); blob_segment{blob_seg_len + 1] = ‘ ’; EXEC SQL FETCH BLOB_CUR INTO :blob_segment :blob_seg_len; } . . . } See Also BASED ON, CLOSE (BLOB), DECLARE CURSOR (BLOB), INSERT CURSOR (BLOB), OPEN (BLOB) GEN_ID( ) Produces a system-generated integer value. Available in SQL, DSQL, and isql. Syntax gen_id (generator, step) Argument Description generator Name of an existing generator step Integer or expression specifying the increment for increasing or decreasing the current generator value. Values can range from –(231) to 231 – 1 Description The GEN_ID() function: 1. Increments the current value of the specified generator by step. 2. Returns the new value of the specified generator. GEN_ID() is useful for automatically producing unique values that can be inserted into a UNIQUE or PRIMARY KEY column. To insert a generated number in a column, write a trigger, procedure, or SQL statement that calls GEN_ID(). Note A generator is initially created with CREATE GENERATOR. By default, the value of a generator begins at zero. It can be set to a different value with SET GENERATOR. Examples The following isql trigger definition includes a call to GEN_ID(): SET TERM !! ; CREATE TRIGGER CREATE_EMPNO FOR EMPLOYEES 122
GRANT BEFORE INSERT POSITION 0 AS BEGIN NEW.EMPNO = GEN_ID (EMPNO_GEN, 1); END SET TERM ; !! The first time the trigger fires, NEW.EMPNO is set to 1. Each subsequent firing increments NEW.EMPNO by 1. See Also CREATE GENERATOR, SET GENERATOR GRANT Assigns privileges to users for specified database objects. Available in SQL, DSQL, and isql. GRANT <privileges> ON [TABLE] {tablename | viewname} TO {<object> | <userlist> | GROUP UNIX_group} | EXECUTE ON PROCEDURE procname TO {<object> | <userlist>} | <role_granted> TO {PUBLIC | <role_grantee_list>}; <privileges> = {ALL [PRIVILEGES] | <privilege_list>} <privilege_list> = SELECT | DELETE | INSERT | UPDATE [(col [, col …])] | REFERENCES [(col [, col …])] [, <privilege_list> …] <object> = PROCEDURE procname | TRIGGER trigname | VIEW viewname | PUBLIC [, <object> …] <userlist> = [USER] username | rolename | Unix_user} [, <userlist> …] [WITH GRANT OPTION] <role_granted> = rolename [, rolename …] LANGUAGE REFERENCE 123
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE <role_grantee_list> = [USER] username [, [USER] username …] [WITH ADMIN OPTION] IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description privilege_list Name of privilege to be granted; valid options are SELECT, DELETE, INSERT, UPDATE, and REFERENCES col Column to which the granted privileges apply tablename Name of an existing table for which granted privileges apply viewname Name of an existing view for which granted privileges apply GROUP unix_group On a UNIX system, the name of a group defined in /etc/group object Name of an existing procedure, trigger, or view; PUBLIC is also a permitted value userlist A user in security.fdb or a rolename created with CREATE ROLE WITH GRANT OPTION Passes GRANT authority for privileges listed in the GRANT statement to userlist rolename An existing role created with the CREATE ROLE statement role_grantee_list A list of users to whom rolename is granted; users must be in security.fdb WITH ADMIN OPTION Passes grant authority for roles listed to role_grantee_list Description GRANT assigns privileges and roles for database objects to users, roles, or other database objects. When an object is first created, only its creator has privileges to it and only its creator can GRANT privileges for it to other users or objects. 124
GRANT g The following table summarizes available privileges: Privilege Enables users to … ALL Perform SELECT, DELETE, INSERT, UPDATE, and REFERENCES SELECT Retrieve rows from a table or view DELETE Remove rows from a table or view INSERT Store new rows in a table or view UPDATE Change the current value in one or more columns in a table or view; can be restricted to a specified subset of columns EXECUTE Execute a stored procedure REFERENCES Reference the specified columns with a foreign key; at a minimum, this must be granted to all the columns of the primary key if it is granted at all Note ALL does not include REFERENCES in code written for Firebird 4.0 or earlier. g To access a table or view, a user or object needs the appropriate SELECT, INSERT, UPDATE, DELETE, or REFERENCES privileges for that table or view. SELECT, INSERT, UPDATE, DELETE, and REFERENCES privileges can be assigned as a unit with ALL. g A user or object must have EXECUTE privilege to call a stored procedure in an application. g To grant privileges to a group of users, create a role using CREATE ROLE. Then use GRANT privilege TO rolename to assign the desired privileges to that role and use GRANT rolename TO user to assign that role to users. Users can be added or removed from a role on a case-by-case basis using GRANT and REVOKE. A user must specify the role at connection time to actually have those privileges. See ANSI SQL 3 roles on page 94 of the Operations Guide for more on invoking a role when connecting to a database. g On UNIX systems, privileges can be granted to groups listed in /etc/groups and to any UNIX user listed in /etc/passwd on both the client and server, as well as to individual users and to roles. g To allow another user to reference a columns from a foreign key, grant REFERENCES privileges on the primary key table or on the table’s primary key columns to the owner of the foreign key table. You must also grant REFERENCES or SELECT privileges on the primary key table to any user who needs to write to the foreign key table. Tip Make it easy: if read security is not an issue, GRANT REFERENCES on the primary key table to PUBLIC. LANGUAGE REFERENCE 125
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE g If you grant the REFERENCES privilege, it must, at a minimum, be granted to all columns of the primary key. When REFERENCES is granted to the entire table, columns that are not part of the primary key are not affected in any way. g When a user defines a foreign key constraint on a table owned by someone else, Firebird checks that that user has REFERENCES privileges on the referenced table. g The privilege is used at runtime to verify that a value entered in a foreign key field is contained in the primary key table. g You can grant REFERENCES privileges to roles. g To give users permission to grant privileges to other users, provide a userlist that includes the WITH GRANT OPTION. Users can grant to others only the privileges that they themselves possess. g To grant privileges to all users, specify PUBLIC in place of a list of user names. Specifying PUBLIC grants privileges only to users, not to database objects. Privileges can be removed only by the user who assigned them, using REVOKE. If ALL privileges are assigned, then ALL privileges must be revoked. If privileges are granted to PUBLIC, they can be removed only for PUBLIC. Examples The following isql statement grants SELECT and DELETE privileges to a user. The WITH GRANT OPTION gives the user GRANT authority. GRANT SELECT, DELETE ON COUNTRY TO CHLOE WITH GRANT OPTION; The next embedded SQL statement, from an embedded program, grants SELECT and UPDATE privileges to a procedure for a table: EXEC SQL GRANT SELECT, UPDATE ON JOB TO PROCEDURE GET_EMP_PROJ; This embedded SQL statement grants EXECUTE privileges for a procedure to another procedure and to a user: EXEC SQL GRANT EXECUTE ON PROCEDURE GET_EMP_PROJ TO PROCEDURE ADD_EMP_PROJ, LUIS; The following example creates a role called “administrator”, grants UPDATE privileges on table1 to that role, and then grants the role to user1, user2, and user3. These users then have UPDATE and REFERENCES privileges on table1. CREATE ROLE administrator; GRANT UPDATE ON table1 TO administrator; GRANT administrator TO user1, user2, user3; See Also REVOKE 126
INSERT For more information about privileges, see the Data Definition Guide. INSERT Adds one or more new rows to a specified table. Available in SQL, DSQL, and isql. Syntax INSERT [TRANSACTION transaction] INTO <object> [(col [, col …])] {VALUES (<val> [, <val> …]) | <select_expr>}; <object> = tablename | viewname <val> = {:variable | <constant> | <expr> | <function> | udf ([<val> [, <val> …]]) | NULL | USER | RDB$DB_KEY | ? } [COLLATE collation] <constant> = num | 'string' | charsetname 'string' <function> = CAST (<val> AS <datatype>) | UPPER (<val>) | GEN_ID (generator, <val>) Argument Description expr A valid SQL expression that results in a single column value select_expr A SELECT that returns zero or more rows and where the number of columns in each row is the same as the number of items to be inserted Notes on the INSERT statement g In SQL and isql, you cannot use val as a parameter placeholder (like “?”). g In DSQL and isql, val cannot be a variable. g You cannot specify a COLLATE clause for Blob columns. LANGUAGE REFERENCE 127
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description TRANSACTION transaction Name of the transaction that controls the execution of the INSERT INTO object Name of an existing table or view into which to insert data col Name of an existing column in a table or view into which to insert values VALUES Lists values to insert into the table or view; values must be listed in the (val [, val …]) same order as the target columns select_expr Query that returns row values to insert into target columns Description INSERT stores one or more new rows of data in an existing table or view. INSERT is one of the database privileges controlled by the GRANT and REVOKE statements. Values are inserted into a row in column order unless an optional list of target columns is provided. If the target list of columns is a subset of available columns, default or NULL values are automatically stored in all unlisted columns. If the optional list of target columns is omitted, the VALUES clause must provide values to insert into all columns in the table. To insert a single row of data, the VALUES clause should include a specific list of values to insert. To insert multiple rows of data, specify a select_expr that retrieves existing data from another table to insert into this one. The selected columns must correspond to the columns listed for insert. IMPORTANT It is legal to select from the same table into which insertions are made, but this practice is not advised because it may result in infinite row insertions. The TRANSACTION clause can be used in multiple transaction SQL applications to specify which transaction controls the INSERT operation. The TRANSACTION clause is not available in DSQL or isql. Examples The following statement, from an embedded SQL application, adds a row to a table, assigning values from host-language variables to two columns: EXEC SQL INSERT INTO EMPLOYEE_PROJECT (EMP_NO, PROJ_ID) VALUES (:emp_no, :proj_id); 128
INSERT CURSOR (BLOB) The next isql statement specifies values to insert into a table with a SELECT statement: INSERT INTO PROJECTS SELECT * FROM NEW_PROJECTS WHERE NEW_PROJECTS.START_DATE > ’6-JUN-1994’; See Also GRANT, REVOKE, SET TRANSACTION, UPDATE INSERT CURSOR (BLOB) Inserts data into a Blob cursor in units of a Blob segment-length or less in size. Available in SQL. Syntax INSERT CURSOR cursor VALUES (:buffer [INDICATOR] :bufferlen); Argument Description cursor Name of the Blob cursor VALUES Clause containing the name and length of the buffer variable to insert :buffer Name of host-variable buffer containing information to insert INDICATOR Indicates that the length of data placed in the buffer follows :bufferlen Length, in bytes, of the buffer to insert Description INSERT CURSOR writes Blob data into a column. Data is written in units equal to or less than the segment size for the Blob. Before inserting data into a Blob cursor: g Declare a local variable, buffer, to contain the data to be inserted. g Declare the length of the variable, bufferlen. g Declare a Blob cursor for INSERT and open it. Each INSERT into the Blob column inserts the current contents of buffer. Between statements fill buffer with new data. Repeat the INSERT until each existing buffer is inserted into the Blob. IMPORTANT INSERT CURSOR requires the INSERT privilege, a table privilege controlled by the GRANT and REVOKE statements. LANGUAGE REFERENCE 129
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Example The following embedded SQL statement shows an insert into the Blob cursor: EXEC SQL INSERT CURSOR BC VALUES (:line INDICATOR :len); See Also CLOSE (BLOB), DECLARE CURSOR (BLOB), FETCH (BLOB), OPEN (BLOB) MAX( ) Retrieves the maximum value in a column. Available in SQL, DSQL, and isql. Syntax MAX ([ALL] <val> | DISTINCT <val>) Argument Description ALL Searches all values in a column DISTINCT Eliminates duplicate values before finding the largest val A column, constant, host-language variable, expression, non-aggregate function, or UDF Description MAX() is an aggregate function that returns the largest value in a specified column, excluding NULL values. If the number of qualifying rows is zero, MAX() returns a NULL value. When MAX() is used on a CHAR, VARCHAR, or Blob text column, the largest value returned varies depending on the character set and collation in use for the column. A default character set can be specified for an entire database with the DEFAULT CHARACTER SET clause in CREATE DATABASE, or specified at the column level with the COLLATE clause in CREATE TABLE. Example The following embedded SQL statement demonstrates the use of SUM(), AVG(), MIN(), and MAX(): EXEC SQL SELECT SUM (BUDGET), AVG (BUDGET), MIN (BUDGET), MAX (BUDGET) FROM DEPARTMENT WHERE HEAD_DEPT = :head_dept INTO :tot_budget, :avg_budget, :min_budget, :max_budget; See Also AVG( ), COUNT( ), CREATE DATABASE, CREATE TABLE, MIN( ), SUM( ) 130
MIN( ) MIN( ) Retrieves the minimum value in a column. Available in SQL, DSQL, and isql. Syntax MIN ([ALL] <val> | DISTINCT <val>) Argument Description ALL Searches all values in a column DISTINCT Eliminates duplicate values before finding the smallest val A column, constant, host-language variable, expression, non-aggregate function, or UDF Description MIN() is an aggregate function that returns the smallest value in a specified column, excluding NULL values. If the number of qualifying rows is zero, MIN() returns a NULL value. When MIN() is used on a CHAR, VARCHAR, or Blob text column, the smallest value returned varies depending on the character set and collation in use for the column. Use the DEFAULT CHARACTER SET clause in CREATE DATABASE to specify a default character set for an entire database, or the COLLATE clause in CREATE TABLE to specify a character set at the column level. Example The following embedded SQL statement demonstrates the use of SUM(), AVG(), MIN(), and MAX(): EXEC SQL SELECT SUM (BUDGET), AVG (BUDGET), MIN (BUDGET), MAX (BUDGET) FROM DEPARTMENT WHERE HEAD_DEPT = :head_dept INTO :tot_budget, :avg_budget, :min_budget, :max_budget; See Also AVG( ), COUNT( ), CREATE DATABASE, CREATE TABLE, MAX( ), SUM( ) OPEN Retrieve specified rows from a cursor declaration. Available in SQL and DSQL. Syntax SQL form: OPEN [TRANSACTION transaction] cursor; LANGUAGE REFERENCE 131
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE DSQL form: OPEN [TRANSACTION transaction] cursor [USING SQL DESCRIPTOR xsqlda] Blob form: See OPEN (BLOB). Argument Description TRANSACTION transaction Name of the transaction that controls execution of OPEN cursor Name of a previously declared cursor to open USING DESCRIPTOR xsqlda Passes the values corresponding to the prepared statement’s parameters through the extended descriptor area (XSQLDA) Description OPEN evaluates the search condition specified in a cursor’s DECLARE CURSOR statement. The selected rows become the active set for the cursor. A cursor is a one-way pointer into the ordered set of rows retrieved by the SELECT in a DECLARE CURSOR statement. It enables sequential access to retrieved rows in turn. There are four related cursor statements: Stage Statement Purpose 1 DECLARE CURSOR Declares the cursor; the SELECT statement determines rows retrieved for the cursor 2 OPEN Retrieves the rows specified for retrieval with DECLARE CURSOR; the resulting rows become the cursor’s active set 3 FETCH Retrieves the current row from the active set, starting with the first row • Subsequent FETCH statements advance the cursor through the set 4 CLOSE Closes the cursor and release system resources Examples The following embedded SQL statement opens a cursor: EXEC SQL OPEN C; See Also CLOSE, DECLARE CURSOR, FETCH OPEN (BLOB) Opens a previously declared Blob cursor and prepares it for read or insert. Available in SQL. 132
PREPARE Syntax OPEN [TRANSACTION name] cursor {INTO | USING} :blob_id; Argument Description TRANSACTION name Specifies the transaction under which the cursor is opened Default: The default transaction cursor Name of the Blob cursor INTO | USING Depending on Blob cursor type, use one of these: INTO: For INSERT BLOB USING: For READ BLOB blob_id Identifier for the Blob column Description OPEN prepares a previously declared cursor for reading or inserting Blob data. Depending on whether the DECLARE CURSOR statement declares a READ or INSERT BLOB cursor, OPEN obtains the value for Blob ID differently: g For a READ BLOB, the blob_id comes from the outer TABLE cursor. g For an INSERT BLOB, the blob_id is returned by the system. Examples The following embedded SQL statements declare and open a Blob cursor: EXEC SQL DECLARE BC CURSOR FOR INSERT BLOB PROJ_DESC INTO PRJOECT; EXEC SQL OPEN BC INTO :blob_id; See Also CLOSE (BLOB), DECLARE CURSOR (BLOB), FETCH (BLOB),INSERT CURSOR (BLOB) PREPARE Prepares a dynamic SQL (DSQL) statement for execution. Available in SQL. LANGUAGE REFERENCE 133
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Syntax PREPARE [TRANSACTION transaction] statement [INTO SQL DESCRIPTOR xsqlda] FROM {:variable | ’string’}; Argument Description TRANSACTION transaction Name of the transaction under control of which the statement is executed statement Establishes an alias for the prepared statement that can be used by subsequent DESCRIBE and EXCUTE statements INTO xsqlda Specifies an XSQLDA to be filled in with the description of the select-list columns in the prepared statement :variable | ’string’ DSQL statement to PREPARE; can be a host-language variable or a string literal Description PREPARE readies a DSQL statement for repeated execution by: g Checking the statement for syntax errors. g Determining datatypes of optionally specified dynamic parameters. g Optimizing statement execution. g Compiling the statement for execution by EXECUTE. PREPARE is part of a group of statements that prepare DSQL statements for execution. Statement Purpose PREPARE Readies a DSQL statement for execution DESCRIBE Fills in the XSQLDA with information about the statement EXECUTE Executes a previously prepared statement EXECUTE IMMEDIATE Prepares a DSQL statement, executes it once, and discards it After a statement is prepared, it is available for execution as many times as necessary during the current session. To prepare and execute a statement only once, use EXECUTE IMMEDIATE. statement establishes a symbolic name for the actual DSQL statement to prepare. It is not declared as a host-language variable. Except for C programs, gpre does not distinguish between uppercase and lowercase in statement, treating “B” and “b” as the same character. For C programs, use the gpre -either_case switch to activate case sensitivity during preprocessing. 134
REVOKE If the optional INTO clause is used, PREPARE also fills in the extended SQL descriptor area (XSQLDA) with information about the datatype, length, and name of select-list columns in the prepared statement. This clause is useful only when the statement to prepare is a SELECT. Note The DESCRIBE statement can be used instead of the INTO clause to fill in the XSQLDA for a select list. The FROM clause specifies the actual DSQL statement to PREPARE. It can be a host-language variable, or a quoted string literal. The DSQL statement to PREPARE can be any SQL data definition, data manipulation, or transaction-control statement. Examples The following embedded SQL statement prepares a DSQL statement from a host-variable statement. Because it uses the optional INTO clause, the assumption is that the DSQL statement in the host variable is a SELECT. EXEC SQL PREPARE Q INTO xsqlda FROM :buf; Note The previous statement could also be prepared and described in the following manner: EXEC SQL PREPARE Q FROM :buf; EXEC SQL DESCRIBE Q INTO SQL DESCRIPTOR xsqlda; See Also DESCRIBE, EXECUTE, EXECUTE IMMEDIATE REVOKE Withdraws privileges from users for specified database objects. Available in SQL, DSQL, and isql. REVOKE [GRANT OPTION FOR] <privileges> ON [TABLE] {tablename | viewname} FROM {<object> | <userlist> | <rolelist> | GROUP UNIX_group} | EXECUTE ON PROCEDURE procname FROM {<object> | <userlist>} | <role_granted> FROM {PUBLIC | <role_grantee_list>}}; <privileges> = {ALL [PRIVILEGES] | <privilege_list>} <privilege_list> = { LANGUAGE REFERENCE 135
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE SELECT | DELETE | INSERT | UPDATE [(col [, col …])] | REFERENCES [(col [, col …])] [, <privilege_list> …]}} <object> ={ PROCEDURE procname | TRIGGER trigname | VIEW viewname | PUBLIC [, <object>]} <userlist> = [USER] username [, [USER] username …] <rolelist> = rolename [, rolename] <role_granted> = rolename [, rolename …] <role_grantee_list> = [USER] username [, [USER] username …] IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description privilege_list Name of privilege to be granted; valid options are SELECT, DELETE, INSERT, UPDATE, and REFERENCES GRANT OPTION FOR Removes grant authority for privileges listed in the REVOKE statement from userlist; cannot be used with object col Column for which the privilege is revoked tablename Name of an existing table for which privileges are revoked viewname Name of an existing view for which privileges are revoked GROUP unix_group On a UNIX system, the name of a group defined in /etc/group object Name of an existing database object from which privileges are to be revoked 136
REVOKE Argument Description userlist A list of users from whom privileges are to be revoked rolename An existing role created with the CREATE ROLE statement role_grantee_list A list of users to whom rolename is granted; users must be in security.fdb Description REVOKE removes privileges from users or other database objects. Privileges are operations for which a user has authority. The following table lists SQL privileges: Privilege Removes a user’s privilege to … ALL Perform SELECT, DELETE, INSERT, UPDATE, REFERENCES, and EXECUTE SELECT Retrieve rows from a table or view DELETE Remove rows from a table or view INSERT Store new rows in a table or view UPDATE Change the current value in one or more columns in a table or view; can be restricted to a specified subset of columns REFERENCES Reference the specified columns with a foreign key; at a minimum, this must be granted to all the columns of the primary key if it is granted at all EXECUTE Execute a stored procedure TABLE 2.9 SQL privileges GRANT OPTION FOR revokes a user’s right to GRANT privileges to other users. The following limitations should be noted for REVOKE: g Only the user who grants a privilege can revoke that privilege. g A single user can be assigned the same privileges for a database object by any number of other users. A REVOKE issued by a user only removes privileges previously assigned by that particular user. g Privileges granted to all users with PUBLIC can only be removed by revoking privileges from PUBLIC. g When a role is revoked from a user, all privileges that granted by that user to others because of authority gained from membership in the role are also revoked. LANGUAGE REFERENCE 137
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Examples The following isql statement takes the SELECT privilege away from a user for a table: REVOKE SELECT ON COUNTRY FROM MIREILLE; The following isql statement withdraws EXECUTE privileges for a procedure from another procedure and a user: REVOKE EXECUTE ON PROCEDURE GET_EMP_PROJ FROM PROCEDURE ADD_EMP_PROJ, LUIS; See Also GRANT ROLLBACK Restores the database to its state prior to the start of the current transaction. Available in SQL, DSQL, and isql. Syntax ROLLBACK [TRANSACTION name] [WORK] [RELEASE]; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description TRANSACTION name Specifies the transaction to roll back in a multiple-transaction application [Default: roll back the default transaction] WORK Optional word allowed for compatibility RELEASE Detaches from all databases after ending the current transaction; SQL only Description ROLLBACK undoes changes made to a database by the current transaction, then ends the transaction. It breaks the program’s connection to the database and frees system resources. Use RELEASE in the last ROLLBACK to close all open databases. Wait until a program no longer needs the database to release system resources. The TRANSACTION clause can be used in multiple-transaction SQL applications to specify which transaction to roll back. If omitted, the default transaction is rolled back. The TRANSACTION clause is not available in DSQL. 138
SELECT Note RELEASE, available only in SQL, detaches from all databases after ending the current transaction. In effect, this option ends database processing. RELEASE is supported for backward compatibility with older versions of Firebird. The preferred method of detaching is with DISCONNECT. Examples The following isql statement rolls back the default transaction: ROLLBACK; The next embedded SQL statement rolls back a named transaction: EXEC SQL ROLLBACK TRANSACTION MYTRANS; See Also COMMIT, DISCONNECT For more information about controlling transactions, see the Embedded SQL Guide. SELECT Retrieves data from one or more tables. Available in SQL, DSQL, and isql. Syntax SELECT [TRANSACTION transaction] [DISTINCT | ALL] {* | <val> [, <val> …]} [INTO :var [, :var …]] FROM <tableref> [, <tableref> …] [WHERE <search_condition>] [GROUP BY col [COLLATE collation] [, col [COLLATE collation] …] LANGUAGE REFERENCE 139
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE [HAVING <search_condition>] [UNION <select_expr> [ALL]] [PLAN <plan_expr>] [ORDER BY <order_list>] [FOR UPDATE [OF col [, col …]]]; <val> = { col [<array_dim>] | :variable | <constant> | <expr> | <function> | udf ([<val> [, <val> …]]) | NULL | USER | RDB$DB_KEY | ? } [COLLATE collation] [AS alias] <array_dim> = [[x:]y [, [x:]y …]] <constant> = num | 'string' | charsetname 'string' <function> = COUNT (* | [ALL] <val> | DISTINCT <val>) | SUM ([ALL] <val> | DISTINCT <val>) | AVG ([ALL] <val> | DISTINCT <val>) | MAX ([ALL] <val> | DISTINCT <val>) | MIN ([ALL] <val> | DISTINCT <val>) | CAST (<val> AS <datatype>) | UPPER (<val>) | GEN_ID (generator, <val>) <tableref> = <joined_table> | table | view | procedure [(<val> [, <val> …])] [alias] <joined_table> = <tableref> <join_type> JOIN <tableref> ON <search_condition> | (<joined_table>) <join_type> = [INNER] JOIN | {LEFT | RIGHT | FULL } [OUTER]} JOIN <search_condition> = <val> <operator> {<val> | (<select_one>)} | <val> [NOT] BETWEEN <val> AND <val> | <val> [NOT] LIKE <val> [ESCAPE <val>] | <val> [NOT] IN (<val> [, <val> …] | <select_list>) | <val> IS [NOT] NULL | <val> {>= | <=} | <val> [NOT] {= | < | >} | {ALL | SOME | ANY} (<select_list>) | EXISTS (<select_expr>) | SINGULAR (<select_expr>) | <val> [NOT] CONTAINING <val> 140
SELECT | <val> [NOT] STARTING [WITH] <val> | (<search_condition>) | NOT <search_condition> | <search_condition> OR <search_condition> | <search_condition> AND <search_condition> <operator> = {= | < | > | <= | >= | !< | !> | <> | !=} <plan_expr> = [JOIN | [SORT] [MERGE]] ({<plan_item> | <plan_expr>} [, {<plan_item> | <plan_expr>} …]) <plan_item> = {table | alias} {NATURAL | INDEX (<index> [, <index> …])| ORDER <index>} <order_list> = {col | int} [COLLATE collation] [ASC[ENDING] | DESC[ENDING]] [, <order_list> …] Argument Description expr A valid SQL expression that results in a single value select_one A SELECT on a single column that returns exactly one value select_list A SELECT on a single column that returns zero or more rows select_expr A SELECT on a list of values that returns zero or more rows Notes on SELECT syntax g When declaring arrays, you must include the outermost brackets, shown below in bold. For example, the following statement creates a 5 by 5 two-dimensional array of strings, each of which is 6 characters long: my_array = varchar(6)[5,5] Use the colon (:) to specify an array with a starting point other than 1. The following example creates an array of integers that begins at 10 and ends at 20: my_array = integer[20:30] g In SQL and isql, you cannot use val as a parameter placeholder (like “?”). g In DSQL and isql, val cannot be a variable. g You cannot specify a COLLATE clause for Blob columns. LANGUAGE REFERENCE 141
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description TRANSACTION transaction Name of the transaction under control of which the statement is executed; SQL only SELECT [DISTINCT | ALL] Specifies data to retrieve. DISTINCT prevents duplicate values from being returned. ALL, the default, retrieves every value {*|val [, val …]} The asterisk (*) retrieves all columns for the specified tables val [, val …] retrieves a list of specified columns, values, and expressions INTO :var [, var …] Singleton select in embedded SQL only; specifies a list of host-language variables into which to retrieve values FROM tableref List of tables, views, and stored procedures from which to retrieve data; list [, tableref …] can include joins and joins can be nested table Name of an existing table in a database view Name of an existing view in a database procedure Name of an existing stored procedure that functions like a SELECT statement alias Brief, alternate name for a table, view, or column; after declaration in tableref, alias can stand in for subsequent references to a table or view joined_table A table reference consisting of a JOIN join_type Type of join to perform. Default: INNER WHERE search_condition Specifies a condition that limits rows retrieved to a subset of all available rows GROUP BY col [, col …] Partitions the results of a query into groups containing all rows with identical values based on a column list COLLATE collation Specifies the collation order for the data retrieved by the query HAVING search_condition Used with GROUP BY; specifies a condition that limits grouped rows returned UNION [ALL] Combines two or more tables that are fully or partially identical in structure; the ALL option keeps identical rows separate instead of folding them together into one 142
SELECT Argument Description PLAN plan_expr Specifies the access plan for the Firebird optimizer to use during retrieval plan_item Specifies a table and index method for a plan ORDER BY order_list Specifies columns to order, either by column name or ordinal number in the query, and the order (ASC or DESC) in which rows to return the rows Description SELECT retrieves data from tables, views, or stored procedures. Variations of the SELECT statement make it possible to: g Retrieve a single row, or part of a row, from a table. This operation is referred to as a singleton select. In embedded applications, all SELECT statements that occur outside the context of a cursor must be singleton selects. g Retrieve multiple rows, or parts of rows, from a table. In embedded applications, multiple row retrieval is accomplished by embedding a SELECT within a DECLARE CURSOR statement. In isql, SELECT can be used directly to retrieve multiple rows. g Retrieve related rows, or parts of rows, from a join of two or more tables. g Retrieve all rows, or parts of rows, from union of two or more tables. LANGUAGE REFERENCE 143
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE All SELECT statements consist of two required clauses (SELECT, FROM), and possibly others (INTO, WHERE, GROUP BY, HAVING, UNION, PLAN, ORDER BY). The following table explains the purpose of each clause, and when they are required: Singleton Multi-row Clause Purpose SELECT SELECT SELECT Lists columns to retrieve Required Required INTO Lists host variables for storing retrieved columns Required Not allowed FROM Identifies the tables to search for values Required Required WHERE Specifies the search conditions used to restrict retrieved Optional Optional rows to a subset of all available rows; a WHERE clause can contain its own SELECT statement, referred to as a subquery GROUP BY Groups related rows based on common column values; used Optional Optional in conjunction with HAVING HAVING Restricts rows generated by GROUP BY to a subset of those Optional Optional rows UNION Combines the results of two or more SELECT statements to Optional Optional produce a single, dynamic table without duplicate rows ORDER BY Specifies which columns to order, either by column name or Optional Optional by ordinal number in the query, and the sort order of rows returned: ascending (ASC) [default] or descending (DESC) PLAN Specifies the query plan that should be used by the query Optional Optional optimizer instead of one it would normally choose FOR UPDATE Specifies columns listed after the SELECT clause of a DECLARE — Optional CURSOR statement that can be updated using a WHERE CURRENT OF clause TABLE 2.10 SELECT statement clauses Because SELECT is such a ubiquitous and complex statement, a meaningful discussion lies outside the scope of this reference. To learn how to use SELECT in isql, see the Operations Guide. For a complete explanation of SELECT and its clauses, see the Embedded SQL Guide. Examples The following isql statement selects columns from a table: SELECT JOB_GRADE, JOB_CODE, JOB_COUNTRY, MAX_SALARY FROM PROJECT; 144
SELECT The next isql statement uses the * wildcard to select all columns and rows from a table: SELECT * FROM COUNTRIES; The following embedded SQL statement uses an aggregate function to count all rows in a table that satisfy a search condition specified in the WHERE clause: EXEC SQL SELECT COUNT (*) INTO :cnt FROM COUNTRY WHERE POPULATION > 5000000; The next isql statement establishes a table alias in the SELECT clause and uses it to identify a column in the WHERE clause: SELECT C.CITY FROM CITIES C WHERE C.POPULATION < 1000000; The following isql statement selects two columns and orders the rows retrieved by the second of those columns: SELECT CITY, STATE FROM CITIES ORDER BY STATE; The next isql statement performs a left join: SELECT CITY, STATE_NAME FROM CITIES C LEFT JOIN STATES S ON S.STATE = C.STATE WHERE C.CITY STARTING WITH ’San’; The following isql statement specifies a query optimization plan for ordered retrieval, utilizing an index for ordering: SELECT * FROM CITIES PLAN (CITIES ORDER CITIES_1); ORDER BY CITY The next isql statement specifies a query optimization plan based on a three-way join with two indexed column equalities: SELECT * FROM CITIES C, STATES S, MAYORS M WHERE C.CITY = M.CITY AND C.STATE = M.STATE PLAN JOIN (STATE NATURAL, CITIES INDEX DUPE_CITY, MAYORS INDEX MAYORS_1); The next example queries two of the system tables, RDB$CHARACTER_SETS and RDB$COLLATIONS to display all the available character sets, their ID numbers, number of bytes per character, and collations. Note the use of ordinal column numbers in the ORDER BY clause. LANGUAGE REFERENCE 145
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE SELECT RDB$CHARACTER_SET_NAME, RDB$CHARACTER_SET_ID, RDB$BYTES_PER_CHARACTER, RDB$COLLATION_NAME FROM RDB$CHARACTER_SETS JOIN RDB$COLLATIONS ON RDB$CHARACTER_SETS.RDB$CHARACTER_SET_ID = RDB%COLLATIONS.RDB$CHARACTER_SET_ID ORDER BY 1, 4; See Also DECLARE CURSOR, DELETE, INSERT, UPDATE For an introduction to using SELECT in isql, see the Operations Guide. For a full discussion of data retrieval in embedded programming using DECLARE CURSOR and SELECT, see the Embedded SQL Guide. SET DATABASE Declares a database handle for database access. Available in SQL. Syntax SET {DATABASE | SCHEMA} dbhandle = [GLOBAL | STATIC | EXTERN][COMPILETIME][FILENAME] ’dbname’ [USER ’name’ PASSWORD ’string’] [RUNTIME [FILENAME] {’dbname’ | :var} [USER {’name’ | :var} PASSWORD {’string’ |:var}]]; Argument Description dbhandle An alias for a specified database • Must be unique within the program• Used in subsequent SQL statements that support database handles GLOBAL [Default] Makes this database declaration available to all modules STATIC Limits scope of this database declaration to the current module EXTERN References a database declaration in another module, rather than actually declaring a new handle COMPILETIME Identifies the database used to look up column references during preprocessing • If only one database is specified in SET DATABASE, it is used both at runtime and compiletime 146
SET DATABASE Argument Description ‘dbname’ Location and path name of the database associated with dbhandle; platform-specific RUNTIME Specifies a database to use at runtime if different than the one specified for use during preprocessing :var Host-language variable containing a database specification, user name, or password USER ‘name’ A valid user name on the server where the database resides • Used with PASSWORD to gain database access on the server• Required for PC client attachments, optional for all others PASSWORD ‘string’ A valid password on the server where the database resides • Used with USER to gain database access on the server• Required for PC client attachments, optional for all others. Description SET DATABASE declares a database handle for a specified database and associates the handle with that database. It enables optional specification of different compile-time and run-time databases. Applications that access multiple databases simultaneously must use SET DATABASE statements to establish separate database handles for each database. dbhandle is an application-defined name for the database handle. Usually handle names are abbreviations of the actual database name. Once declared, database handles can be used in subsequent CONNECT, COMMIT, and ROLLBACK statements. They can also be used within transactions to differentiate table names when two or more attached databases contain tables with the same names. dbname is a platform-specific file specification for the database to associate with dbhandle. It should follow the file syntax conventions for the server where the database resides. GLOBAL, STATIC, and EXTERN are optional parameters that determine the scope of a database declaration. The default scope, GLOBAL, means that a database handle is available to all code modules in an application. STATIC limits database handle availability to the code module where the handle is declared. EXTERN references a global database handle in another module. The optional COMPILETIME and RUNTIME parameters enable a single database handle to refer to one database when an application is preprocessed, and to another database when an application is run by a user. If omitted, or if only a COMPILETIME database is specified, Firebird uses the same database during preprocessing and at run time. LANGUAGE REFERENCE 147
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE The USER and PASSWORD parameters are required for all PC client applications, but are optional for all other remote attachments. The user name and password are verified by the server in the security database before permitting remote attachments to succeed. Examples The following embedded SQL statement declares a handle for a database: EXEC SQL SET DATABASE DB1 = ’employee.fdb’; The next embedded SQL statement declares different databases at compile time and run time. It uses a host-language variable to specify the run-time database. EXEC SQL SET DATABASE EMDBP = ’employee.fdb’ RUNTIME :db_name; See Also COMMIT, CONNECT, ROLLBACK, SELECT For more information on the security database, see the Operations Guide. SET GENERATOR Sets a new value for an existing generator. Available in SQL, DSQL, and isql. Syntax SET GENERATOR name TO int; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing generator int Value to which to set the generator, an integer from –231 to 231 – 1 Description SET GENERATOR initializes a starting value for a newly created generator, or resets the value of an existing generator. A generator provides a unique, sequential numeric value through the GEN_ID() function. If a newly created generator is not initialized with SET GENERATOR, its starting value defaults to zero. int is the new value for the generator. When the GEN_ID() function inserts or updates a value in a column, that value is int plus the increment specified in the GEN_ID() step parameter. 148
SET NAMES Tip To force a generator’s first insertion value to 1, use SET GENERATOR to specify a starting value of 0, and set the step value of the GEN_ID() function to 1. IMPORTANT When resetting a generator that supplies values to a column defined with PRIMARY KEY or UNIQUE integrity constraints, be careful that the new value does not enable duplication of existing column values, or all subsequent insertions and updates will fail. Example The following isql statement sets a generator value to 1,000: SET GENERATOR CUST_NO_GEN TO 1000; If GEN_ID() now calls this generator with a step value of 1, the first number it returns is 1,001. See Also CREATE GENERATOR, CREATE PROCEDURE, CREATE TRIGGER, GEN_ID( ) SET NAMES Specifies an active character set to use for subsequent database attachments. Available in SQL, and isql. Syntax SET NAMES [charset | :var]; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description charset Name of a character set that identifies the active character set for a given process; default: NONE :var Host variable containing string identifying a known character set name • Must be declared as a character set name• SQL only Description SET NAMES specifies the character set to use for subsequent database attachments in an application. It enables the server to translate between the default character set for a database on the server and the character set used by an application on the client. SET NAMES must appear before the SET DATABASE and CONNECT statements it is to affect. Tip Use a host-language variable with SET NAMES in an embedded application to specify a character set interactively. LANGUAGE REFERENCE 149
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE For a complete list of character sets recognized by Firebird, see Chapter 8, “Character Sets and Collation Orders.” Choice of character sets limits possible collation orders to a subset of all available collation orders. Given a specific character set, a specific collation order can be specified when data is selected, inserted, or updated in a column. IMPORTANT If you do not specify a default character set, the character set defaults to NONE. Using character set NONE means that there is no character set assumption for columns; data is stored and retrieved just as you originally entered it. You can load any character set into a column defined with NONE, but you cannot load that same data into another column that has been defined with a different character set. No transliteration is performed between the source and destination character sets, so in most cases, errors occur during assignment. Example The following statements demonstrate the use of SET NAMES in an embedded SQL application: EXEC SQL SET NAMES ISO8859_1; EXEC SQL SET DATABASE DB1 = ’employee.fdb’; EXEC SQL CONNECT; The next statements demonstrate the use of SET NAMES in isql: SET NAMES LATIN1; CONNECT ’employee.fdb’; See Also CONNECT, SET DATABASE For more information about character sets and collation orders, see the Data Definition Guide. SET SQL DIALECT Declares the SQL Dialect for database access. Available in gpre, isql, wisql, and SQL. Syntax SET SQL DIALECT n; Argument Description n The SQL Dialect type, either 1, 2, or 3 150
SET STATISTICS Description SET SQL DIALECT declares the SQL Dialect for database access. n is the SQL Dialect type, either 1, 2, or 3. If no dialect is specified, the default dialect is set to that of the specified compile-time database. If the default dialect is different than the one specified by the user, a warning is generated and the the default dialect is set to the user-specified value SQL Dialect Used for 1 Firebird 5.5 and earlier compatibility 2 Transitional dialect used to flag changes when migrating from dialect 1 to dialect 3 3 Firebird 6.0; allows you to use delimited identifiers, exact numerics, and DATE, TIME, and TIMESTAMP datatypes TABLE 2.11 SQL Dialects Examples The following embedded SQL statement sets the SQL Dialect to 3: EXEC SQL SET SQL DIALECT 3; See Also SHOW SQL DIALECT SET STATISTICS Recomputes the selectivity of a specified index. Available in SQL, DSQL, and isql. Syntax SET STATISTICS INDEX name; IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description name Name of an existing index for which to recompute selectivity LANGUAGE REFERENCE 151
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Description SET STATISTICS enables the selectivity of an index to be recomputed. Index selectivity is a calculation, based on the number of distinct rows in a table, that is made by the Firebird optimizer when a table is accessed. It is cached in memory, where the optimizer can access it to calculate the optimal retrieval plan for a given query. For tables where the number of duplicate values in indexed columns radically increases or decreases, periodically recomputing index selectivity can improve performance. Only the creator of an index can use SET STATISTICS. Note SET STATISTICS does not rebuild an index. To rebuild an index, use ALTER INDEX. Example The following embedded SQL statement recomputes the selectivity for an index: EXEC SQL SET STATISTICS INDEX MINSALX; See Also ALTER INDEX, CREATE INDEX, DROP INDEX SET TRANSACTION Starts a transaction and optionally specifies its behavior. Available in SQL, DSQL, and isql. Syntax SET TRANSACTION [NAME transaction] [READ WRITE | READ ONLY] [WAIT | NO WAIT] [[ISOLATION LEVEL] {SNAPSHOT [TABLE STABILITY] | READ COMMITTED [[NO] RECORD_VERSION]}] [RESERVING <reserving_clause> | USING dbhandle [, dbhandle …]]; <reserving_clause> = table [, table …] [FOR [SHARED | PROTECTED] {READ | WRITE}] [, <reserving_clause>] IMPORTANT In SQL statements passed to DSQL, omit the terminating semicolon. In embedded applications written in C and C++, and in isql, the semicolon is a terminating symbol for the statement, so it must be included. Argument Description NAME transaction Specifies the name for this transaction • transaction is a previously declared and initialized host-language variable• SQL only READ WRITE [Default] Specifies that the transaction can read and write to tables 152
SET TRANSACTION Argument Description READ ONLY Specifies that the transaction can only read tables WAIT [Default] Specifies that a transaction wait for access if it encounters a lock conflict with another transaction NO WAIT Specifies that a transaction immediately return an error if it encounters a lock conflict ISOLATION LEVEL Specifies the isolation level for this transaction when attempting to access the same tables as other simultaneous transactions; default: SNAPSHOT RESERVING Reserves lock for tables at transaction start reserving_clause USING dbhandle Limits database access to a subset of available databases; SQL only [, dbhandle …] Description SET TRANSACTION starts a transaction, and optionally specifies its database access, lock conflict behavior, and level of interaction with other concurrent transactions accessing the same data. It can also reserve locks for tables. As an alternative to reserving tables, multiple database SQL applications can restrict a transaction’s access to a subset of connected databases. IMPORTANT Applications preprocessed with the gpre -manual switch must explicitly start each transaction with a SET TRANSACTION statement. SET TRANSACTION affects the default transaction unless another transaction is specified in the optional NAME clause. Named transactions enable support for multiple, simultaneous transactions in a single application. All transaction names must be declared as host-language variables at compile time. In DSQL, this restriction prevents dynamic specification of transaction names. By default a transaction has READ WRITE access to a database. If a transaction only needs to read data, specify the READ ONLY parameter. When simultaneous transactions attempt to update the same data in tables, only the first update succeeds. No other transaction can update or delete that data until the controlling transaction is rolled back or committed. By default, transactions WAIT until the controlling transaction ends, then attempt their own operations. To force a transaction to return immediately and report a lock conflict error without waiting, specify the NO WAIT parameter. LANGUAGE REFERENCE 153
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE ISOLATION LEVEL determines how a transaction interacts with other simultaneous transactions accessing the same tables. The default ISOLATION LEVEL is SNAPSHOT. It provides a repeatable-read view of the database at the moment the transaction starts. Changes made by other simultaneous transactions are not visible. SNAPSHOT TABLE STABILITY provides a repeatable read of the database by ensuring that transactions cannot write to tables, though they may still be able to read from them. READ COMMITTED enables a transaction to see the most recently committed changes made by other simultaneous transactions. It can also update rows as long as no update conflict occurs. Uncommitted changes made by other transactions remain invisible until committed. READ COMMITTED also provides two optional parameters: g NO RECORD_VERSION, the default, reads only the latest version of a row. If the WAIT lock resolution option is specified, then the transaction waits until the latest version of a row is committed or rolled back, and retries its read. g RECORD_VERSION reads the latest committed version of a row, even if more recent uncommitted version also resides on disk. The RESERVING clause enables a transaction to register its desired level of access for specified tables when the transaction starts instead of when the transaction attempts its operations on that table. Reserving tables at transaction start can reduce the possibility of deadlocks. The USING clause, available only in SQL, can be used to conserve system resources by limiting the number of databases a transaction can access. Examples The following embedded SQL statement sets up the default transaction with an isolation level of READ COMMITTED. If the transaction encounters an update conflict, it waits to get control until the first (locking) transaction is committed or rolled back. EXEC SQL SET TRANSACTION WAIT ISOLATION LEVEL READ COMMITTED; The next embedded SQL statement starts a named transaction: EXEC SQL SET TRANSACTION NAME T1 READ COMMITTED; The following embedded SQL statement reserves three tables: EXEC SQL SET TRANSACTION NAME TR1 ISOLATION LEVEL READ COMMITTED NO RECORD_VERSION WAIT RESERVING TABLE1, TABLE2 FOR SHARED WRITE, TABLE3 FOR PROTECTED WRITE; 154
SHOW SQL DIALECT See Also COMMIT, ROLLBACK, SET NAMES For more information about transactions, see the Embedded SQL Guide. SHOW SQL DIALECT Returns the current client SQL Dialect setting and the database SQL Dialect value. Available in gpre, isql, wisql, and SQL. Syntax SHOW SQL DIALECT; Description SHOW SQL DIALECT returns the current client SQL Dialect setting and the database SQL Dialect value, either 1, 2, or 3. SQL Dialect Used for 1 Firebird 0.x and earlier compatibility 2 Transitional dialect used to flag changes when migrating from dialect 1 to dialect 3 (Not used) 3 Firebird 1.0; allows you to use delimited identifiers, exact numerics, and DATE, TIME, and TIMESTAMP datatypes TABLE 2.12 SQL Dialects Examples The following embedded SQL statement returns the SQL Dialect: EXEC SQL SHOW SQL DIALECT; See Also SET SQL DIALECT LANGUAGE REFERENCE 155
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE SUM( ) Totals the numeric values in a specified column. Available in SQL, DSQL, and isql. Syntax SUM ([ALL] <val> | DISTINCT <val>) Argument Description ALL Totals all values in a column DISTINCT Eliminates duplicate values before calculating the total val A column, constant, host-language variable, expression, non-aggregate function, or UDF that evaluates to a numeric datatype Description SUM() is an aggregate function that calculates the sum of numeric values for a column. If the number of qualifying rows is zero, SUM() returns a NULL value. Example The following embedded SQL statement demonstrates the use of SUM(), AVG(), MIN(), and MAX(): EXEC SQL SELECT SUM (BUDGET), AVG (BUDGET), MIN (BUDGET), MAX (BUDGET) FROM DEPARTMENT WHERE HEAD_DEPT = :head_dept INTO :tot_budget, :avg_budget, :min_budget, :max_budget; See Also AVG( ), COUNT( ), MAX( ), MIN( ) UPDATE Changes the data in all or part of an existing row in a table, view, or active set of a cursor. Available in SQL, DSQL, and isql. Syntax SQL form: UPDATE [TRANSACTION transaction] {table | view} SET col = <val> [, col = <val> …] [WHERE <search_condition> | WHERE CURRENT OF cursor]; DSQL and isql form: UPDATE {table | view} SET col = <val> [, col = <val> …] [WHERE <search_condition> 156
UPDATE <val> = { col [<array_dim>] | :variable | <constant> | <expr> | <function> | udf ([<val> [, <val> …]]) | NULL | USER | ?} [COLLATE collation] <array_dim> = [[x:]y [, [x:]y …]] <constant> = num | 'string' | charsetname 'string' <function> = CAST (<val> AS <datatype>) | UPPER (<val>) | GEN_ID (generator, <val>) <expr> = A valid SQL expression that results in a single value. <search_condition> = See CREATE TABLE for a full description. Notes on the UPDATE statement g In SQL and isql, you cannot use val as a parameter placeholder (like “?”). g In DSQL and isql, val cannot be a variable. g You cannot specify a COLLATE clause for Blob columns. Argument Description TRANSACTION transaction Name of the transaction under control of which the statement is executed table | view Name of an existing table or view to update. SET col = val Specifies the columns to change and the values to assign to those columns WHERE search_condition Searched update only; specifies the conditions a row must meet to be modified WHERE CURRENT OF cursor Positioned update only; specifies that the current row of a cursor’s active set is to be modified • Not available in DSQL and isql LANGUAGE REFERENCE 157
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE Description UPDATE modifies one or more existing rows in a table or view. UPDATE is one of the database privileges controlled by GRANT and REVOKE. For searched updates, the optional WHERE clause can be used to restrict updates to a subset of rows in the table. Searched updates cannot update array slices. IMPORTANT Without a WHERE clause, a searched update modifies all rows in a table. When performing a positioned update with a cursor, the WHERE CURRENT OF clause must be specified to update one row at a time in the active set. Note When updating a Blob column, UPDATE replaces the entire Blob with a new value. Examples The following isql statement modifies a column for all rows in a table: UPDATE CITIES SET POPULATION = POPULATION * 1.03; The next embedded SQL statement uses a WHERE clause to restrict column modification to a subset of rows: EXEC SQL UPDATE PROJECT SET PROJ_DESC = :blob_id WHERE PROJ_ID = :proj_id; See Also DELETE, GRANT, INSERT, REVOKE, SELECT UPPER( ) Converts a string to all uppercase. Available in SQL, DSQL, and isql. Syntax UPPER (<val>) Argument Description val A column, constant, host-language variable, expression, function, or UDF that evaluates to a character datatype Description UPPER() converts a specified string to all uppercase characters. If applied to character sets that have no case differentiation, UPPER() has no effect. 158
WHENEVER Examples The following isql statement changes the name, BMatthews, to BMATTHEWS: UPDATE EMPLOYEE SET EMP_NAME = UPPER (BMatthews) WHERE EMP_NAME = ’BMatthews’; The next isql statement creates a domain called PROJNO with a CHECK constraint that requires the value of the column to be all uppercase: CREATE DOMAIN PROJNO AS CHAR(5) CHECK (VALUE = UPPER (VALUE)); See Also CAST( ) WHENEVER Traps SQLCODE errors and warnings. Available in SQL. Syntax WHENEVER {NOT FOUND | SQLERROR | SQLWARNING} {GOTO label | CONTINUE}; Argument Description NOT FOUND Traps SQLCODE = 100, no qualifying rows found for the executed statement SQLERROR Traps SQLCODE < 0, failed statement SQLWARNING Traps SQLCODE > 0 AND < 100, system warning or informational message GOTO label Jumps to program location specified by label when a warning or error occurs CONTINUE Ignores the warning or error and attempts to continue processing Description WHENEVER traps for SQLCODE errors and warnings. Every executable SQL statement returns an SQLCODE value to indicate its success or failure. If SQLCODE is zero, statement execution is successful. A non-zero value indicates an error, warning, or not found condition. If the appropriate condition is trapped for, WHENEVER can: g Use GOTO label to jump to an error-handling routine in an application. g Use CONTINUE to ignore the condition. LANGUAGE REFERENCE 159
CHAPTER 2 SQL STATEMENT AND FUNCTION REFERENCE WHENEVER can help limit the size of an application, because the application can use a single suite of routines for handling all errors and warnings. WHENEVER statements should precede any SQL statement that can result in an error. Each condition to trap for requires a separate WHENEVER statement. If WHENEVER is omitted for a particular condition, it is not trapped. Tip Precede error-handling routines with WHENEVER … CONTINUE statements to prevent the possibility of infinite looping in the error-handling routines. Example In the following code from an embedded SQL application, three WHENEVER statements determine which label to branch to for error and warning handling: EXEC SQL WHENEVER SQLERROR GO TO Error; /* Trap all errors. */ EXEC SQL WHENEVER NOT FOUND GO TO AllDone; /* Trap SQLCODE = 100 */ EXEC SQL WHENEVER SQLWARNING CONTINUE; /* Ignore all warnings. */ For a complete discussion of error-handling methods and programming, see the Embedded SQL Guide. 160
CHAPTER 3 Procedures and Triggers Chapter 3 Firebird procedure and trigger language is a complete programming language for writing stored procedures and triggers in isql and DSQL. It includes: g SQL data manipulation statements: INSERT, UPDATE, DELETE, and singleton SELECT. g Powerful extensions to SQL, including assignment statements, control-flow statements, context variables, event-posting, exceptions, and error handling. Although stored procedures and triggers are used in entirely different ways and for different purposes, they both use procedure and trigger language. Both triggers and stored procedures can use any statements in procedure and trigger language, with some exceptions: g OLD and NEW context variables are unique to triggers. g Input and output parameters, and the SUSPEND and EXIT statements are unique to stored procedures. The Data Definition Guide explains how to create and use stored procedures and triggers. This chapter is a reference for the statements that are unique to trigger and procedure language or that have special syntax when used in triggers and procedures. LANGUAGE REFERENCE 161
CHAPTER 3 PROCEDURES AND TRIGGERS Creating triggers and stored procedures Stored procedures and triggers are defined with the CREATE PROCEDURE and CREATE TRIGGER statements, respectively. Each of these statements is composed of a header and a body. The header contains: g The name of the procedure or trigger, unique within the database. g For a trigger: · A table name, identifying the table that causes the trigger to fire. · Statements that determine when the trigger fires. g For a stored procedure: · An optional list of input parameters and their datatypes. · If the procedure returns values to the calling program, a list of output parameters and their datatypes. The body contains: g An optional list of local variables and their datatypes. g A block of statements in Firebird procedure and trigger language, bracketed by BEGIN and END. A block can itself include other blocks, so that there may be many levels of nesting. IMPORTANT Because each statement in a stored procedure body must be terminated by a semicolon, you must define a different symbol to terminate the CREATE PROCEDURE statement in isql. Use SET TERM before CREATE PROCEDURE to specify a terminator other than a semicolon. After the CREATE PROCEDURE statement, include another SET TERM to change the terminator back to a semicolon. 162
NOMENCLATURE CONVENTIONS Nomenclature conventions This chapter uses the following nomenclature: g A block is one or more compound statements enclosed by BEGIN and END. g A compound statement is either a block or a statement. g A statement is a single statement in procedure and trigger language. To illustrate in a syntax diagram: <block> = BEGIN <compound_statement> [<compound_statement> …] END <compound_statement> = {<block> | statement;} Assignment statement Assigns a value to an input or output parameter or local variable. Available in triggers and stored procedures. Syntax variable = <expression>; Argument Description variable A local variable, input parameter, or output parameter expression Any valid combination of variables, SQL operators, and expressions, including user-defined functions (UDFs) and generators Description An assignment statement sets the value of a local variable, input parameter, or output parameter. Variables must be declared before they can be used in assignment statements. Example The first assignment statement below sets the value of x to 9. The second statement sets the value of y at twice the value of x. The third statement uses an arithmetic expression to assign z a value of 3. DECLARE VARIABLE x INTEGER; DECLARE VARIABLE y INTEGER; DECLARE VARIABLE z INTEGER; LANGUAGE REFERENCE 163
CHAPTER 3 PROCEDURES AND TRIGGERS x = 9; y = 2 * x; z = 4 * x / (y - 6); See Also DECLARE VARIABLE, Input parameters, Output parameters BEGIN … END Defines a block of statements executed as one. Available in triggers and stored procedures. Syntax <block> = BEGIN <compound_statement> [<compound_statement> …] END <compound_statement> = {<block> | statement;} Description Each block of statements in the procedure body starts with a BEGIN statement and ends with an END statement. As shown in the above syntax diagram, a block can itself contain other blocks, so there may be many levels of nesting. BEGIN and END are not followed by a semicolon. In isql, the final END in the procedure body is followed by the terminator specified by SET TERM. The final END statement in a trigger terminates the trigger. The final END statement in a stored procedure operates differently, depending on the type of procedure: g In a select procedure, the final END statement returns control to the application and sets SQLCODE to 100, which indicates there are no more rows to retrieve. g In an executable procedure, the final END statement returns control and current values of output parameters, if any, to the calling application. Example The following isql fragment of the DELETE_EMPLOYEE procedure shows two examples of BEGIN … END blocks. SET TERM !! ; CREATE PROCEDURE DELETE_EMPLOYEE (EMP_NUM INTEGER) AS DECLARE VARIABLE ANY_SALES INTEGER; BEGIN ANY_SALES = 0; . . . 164
COMMENT IF (ANY_SALES > 0) THEN BEGIN EXCEPTION REASSIGN_SALES; EXIT; END . . . END !! See Also EXIT, SUSPEND Comment Allows programmers to add comments to procedure and trigger code. Available in triggers and stored procedures. Syntax /* comment_text */ Argument Description comment_text Any number of lines of comment text Description Comments can be placed on the same line as code, or on separate lines. It is good programming practice to state the input and output parameters of a procedure in a comment preceding the procedure. It is also often useful to comment local variable declarations to indicate what each variable is used for. Example The following isql procedure fragment illustrates some ways to use comments: /* * Procedure DELETE_EMPLOYEE : Delete an employee. * * Parameters: * employee number * Returns: * -- */ CREATE PROCEDURE DELETE_EMPLOYEE (EMP_NUM INTEGER) AS DECLARE VARIABLE ANY_SALES INTEGER; /* Number of sales for emp. /* BEGIN . . . LANGUAGE REFERENCE 165
CHAPTER 3 PROCEDURES AND TRIGGERS DECLARE VARIABLE Declares a local variable. Available in triggers and stored procedures. Syntax DECLARE VARIABLE var datatype; Argument Description var Name of the local variable, unique within the trigger or procedure datatype Datatype of the local variable; can be any Firebird datatype except Blob and arrays Description Local variables are declared and used within a stored procedure. They have no effect outside the procedure. Local variables must be declared at the beginning of a procedure body before they can be used. Each local variable requires a separate DECLARE VARIABLE statement, followed by a semicolon (;). Example The following header declares the local variable, ANY_SALES: CREATE PROCEDURE DELETE_EMPLOYEE (EMP_NUM INTEGER) AS DECLARE VARIABLE ANY_SALES INTEGER; BEGIN . . . See Also Input parameters, Output parameters EXCEPTION Raises the specified exception. Available in triggers and stored procedures. Syntax EXCEPTION name; Argument Description name Name of the exception being raised Description An exception is a user-defined error that has a name and an associated text message. When raised, an exception: 166
EXECUTE PROCEDURE g Terminates the procedure or trigger in which it was raised and undoes any actions performed (directly or indirectly) by the procedure or trigger. g Returns an error message to the calling application. In isql, the error message is displayed to the screen. Exceptions can be handled with the WHEN statement. If an exception is handled, it will behave differently. Example The following isql statement defines an exception named REASSIGN_SALES: CREATE EXCEPTION REASSIGN_SALES ’Reassign the sales records before deleting this employee.’ !! Then these statements from a procedure body raise the exception: IF (ANY_SALES > 0) THEN EXCEPTION REASSIGN_SALES; See Also WHEN … DO For more information on creating exceptions, see CREATE EXCEPTION on page 57. EXECUTE PROCEDURE Executes a stored procedure. Available in triggers and stored procedures. Syntax EXECUTE PROCEDURE name [:param [, :param …]] [RETURNING_VALUES :param [, :param …]]; Argument Description name Name of the procedure being executed. Must have been previously defined to the database with CREATE PROCEDURE [param [, param …]] List of input parameters, if the procedure requires them • Can be constants or variables• Precede variables with a colon, except NEW and OLD context variables [RETURNING_VALUES param List of output parameters, if the procedure returns values; precede [, param …]] each with a colon, except NEW and OLD context variables Description A stored procedure can itself execute a stored procedure. Each time a stored procedure calls another procedure, the call is said to be nested because it occurs in the context of a previous and still active call to the first procedure. A stored procedure called by another stored procedure is known as a nested procedure. LANGUAGE REFERENCE 167
CHAPTER 3 PROCEDURES AND TRIGGERS If a procedure calls itself, it is recursive. Recursive procedures are useful for tasks that involve repetitive steps. Each invocation of a procedure is referred to as an instance, since each procedure call is a separate entity that performs as if called from an application, reserving memory and stack space as required to perform its tasks. Note Stored procedures can be nested up to 1,000 levels deep. This limitation helps to prevent infinite loops that can occur when a recursive procedure provides no absolute terminating condition. Nested procedure calls may be restricted to fewer than 1,000 levels by memory and stack limitations of the server. Example The following isql example illustrates a recursive procedure, FACTORIAL, which calculates factorials. The procedure calls itself recursively to calculate the factorial of NUM, the input parameter. SET TERM !!; CREATE PROCEDURE FACTORIAL (NUM INT) RETURNS (N_FACTORIAL DOUBLE PRECISION) AS DECLARE VARIABLE NUM_LESS_ONE INT; BEGIN IF (NUM = 1) THEN BEGIN /**** Base case: 1 factorial is 1 ****/ N_FACTORIAL = 1; EXIT; END ELSE BEGIN /**** Recursion: num factorial = num * (num-1) factorial ****/ NUM_LESS_ONE = NUM - 1; EXECUTE PROCEDURE FACTORIAL NUM_LESS_ONE RETURNING_VALUES N_FACTORIAL; N_FACTORIAL = N_FACTORIAL * NUM; EXIT; END END!! SET TERM ;!! See Also CREATE PROCEDURE, Input parameters, Output parameters For more information on executing procedures, see EXECUTE PROCEDURE on page 118. 168
EXIT EXIT Jumps to the final END statement in the procedure. Available in stored procedures only. Syntax EXIT; Description In both select and executable procedures, EXIT jumps program control to the final END statement in the procedure. What happens when a procedure reaches the final END statement depends on the type of procedure: g In a select procedure, the final END statement returns control to the application and sets SQLCODE to 100, which indicates there are no more rows to retrieve. g In an executable procedure, the final END statement returns control and values of output parameters, if any, to the calling application. SUSPEND also returns values to the calling program. Each of these statements has specific behavior for executable and select procedures, as shown in the following table. Procedure type SUSPEND EXIT END Select • Suspends execution of Jumps to final END • Returns control to application procedure procedure until next • Sets SQLCODE to 100 (end of FETCH is issued record stream) • Returns output values Executable • Jumps to final END Jumps to final END • Returns values procedure • Not Recommended • Returns control to application TABLE 3.1 SUSPEND, EXIT, and END Example Consider the following procedure from an isql script: SET TERM !!; CREATE PROCEDURE P RETURNS (r INTEGER) AS BEGIN r = 0; WHILE (r < 5) DO BEGIN r = r + 1; SUSPEND; IF (r = 3) THEN EXIT; LANGUAGE REFERENCE 169
CHAPTER 3 PROCEDURES AND TRIGGERS END END!! SET TERM ;!! If this procedure is used as a select procedure in isql, for example, SELECT * FROM P; then it returns values 1, 2, and 3 to the calling application, since the SUSPEND statement returns the current value of r to the calling application. The procedure terminates when it encounters EXIT. If the procedure is used as an executable procedure in isql, for example, EXECUTE PROCEDURE P; it returns 1, since the SUSPEND statement will terminate the procedure and return the current value of r to the calling application. SUSPEND should not be used in an executable procedure, so EXIT would be used instead. See Also BEGIN … END, SUSPEND FOR SELECT…DO Repeats a block or statement for each row retrieved by the SELECT statement. Available in triggers and stored procedures. Syntax FOR <select_expr> DO <compound_statement> Argument Description select_expr SELECT statement that retrieves rows from the database; the INTO clause is required and must come last compound_statement Statement or block executed once for each row retrieved by the SELECT statement Description FOR SELECT is a loop statement that retrieves the row specified in the select_expr and performs the statement or block following DO for each row retrieved. The select_expr is a normal SELECT, except the INTO clause is required and must be the last clause. 170
IF…THEN … ELSE Example The following isql statement selects department numbers into the local variable, RDNO, which is then used as an input parameter to the DEPT_BUDGET procedure: FOR SELECT DEPT_NO FROM DEPARTMENT WHERE HEAD_DEPT = :DNO INTO :RDNO DO BEGIN EXECUTE PROCEDURE DEPT_BUDGET :RDNO RETURNING_VALUES :SUMB; TOT = TOT + SUMB; END See Also SELECT IF…THEN … ELSE Conditional statement that performs a block or statement in the IF clause if the specified condition is TRUE, otherwise performs the block or statement in the optional ELSE clause. Available in triggers and stored procedures. Syntax IF (<condition>) THEN <compound_statement> [ELSE <compound_statement>] Argument Description condition Boolean expression that evaluates to TRUE, FALSE, or UNKNOWN; must be enclosed in parentheses THEN compound_statement Statement or block executed if condition is TRUE ELSE compound_statement Optional statement or block executed if condition is not TRUE Description The IF … THEN … ELSE statement selects alternative courses of action by testing a specified condition. condition is an expression that must evaluate to TRUE to execute the statement or block following THEN. The optional ELSE clause specifies an alternative statement or block executed if condition is not TRUE. LANGUAGE REFERENCE 171
CHAPTER 3 PROCEDURES AND TRIGGERS Example The following lines of code illustrate the use of IF… THEN, assuming the variables LINE2, FIRST, and LAST have been previously declared: . . . IF (FIRST IS NOT NULL) THEN LINE2 = FIRST || ’ ’ || LAST; ELSE LINE2 = LAST; . . . See Also WHILE … DO Input parameters Used to pass values from an application to a stored procedure. Available in stored procedures only. Syntax CREATE PROCEDURE name [(param datatype [, param datatype …])] Description Input parameters are used to pass values from an application to a stored procedure. They are declared in a comma-delimited list in parentheses following the procedure name in the header of CREATE PROCEDURE. Once declared, they can be used in the procedure body anywhere a variable can appear. Input parameters are passed by value from the calling program to a stored procedure. This means that if the procedure changes the value of an input variable, the change has effect only within the procedure. When control returns to the calling program, the input variable will still have its original value. Input parameters can be of any Firebird datatype except Blob. Arrays of datatypes are also unsupported. Example The following procedure header, from an isql script, declares two input parameters, EMP_NO and PROJ_ID: CREATE PROCEDURE ADD_EMP_PROJ (EMP_NO SMALLINT, PROJ_ID CHAR(5)) AS . . . See Also DECLARE VARIABLE For more information on declaring input parameters in a procedure header, see CREATE PROCEDURE on page 61. 172
NEW CONTEXT VARIABLES NEW context variables Indicates a new column value in an INSERT or UPDATE operation. Available only in triggers. Syntax NEW.column Argument Description column Name of a column in the affected row Description Triggers support two context variables: OLD and NEW. A NEW context variable refers to the new value of a column in an INSERT or UPDATE operation. Context variables are often used to compare the values of a column before and after it is modified. Context variables can be used anywhere a regular variable can be used. New values for a row can only be altered before actions. A trigger that fires after INSERT and tries to assign a value to NEW.column will have no effect. However, the actual column values are not altered until after the action, so triggers that reference values from their target tables will not see a newly inserted or updated value unless they fire after UPDATE or INSERT. Example The following isql script is a trigger that fires after the EMPLOYEE table is updated, and compares an employee’s old and new salary. If there is a change in salary, the trigger inserts an entry in the SALARY_HISTORY table. SET TERM !! ; CREATE TRIGGER SAVE_SALARY_CHANGE FOR EMPLOYEE AFTER UPDATE AS BEGIN IF (OLD.SALARY <> NEW.SALARY) THEN INSERT INTO SALARY_HISTORY (EMP_NO, CHANGE_DATE, UPDATER_ID, OLD_SALARY, PERCENT_CHANGE) VALUES (OLD.EMP_NO, ’NOW’, USER, OLD.SALARY, (NEW.SALARY - OLD.SALARY) * 100 / OLD.SALARY); END !! SET TERM ; !! See Also OLD context variables For more information on creating triggers, see CREATE TRIGGER on page 80. LANGUAGE REFERENCE 173
CHAPTER 3 PROCEDURES AND TRIGGERS OLD context variables Indicates a current column value in an UPDATE or DELETE operation. Available in triggers only. Syntax OLD.column Argument Description column Name of a column in the affected row Description Triggers support two context variables: OLD and NEW. An OLD context variable refers to the current or previous value of a column in an INSERT or UPDATE operation. Context variables are often used to compare the values of a column before and after it is modified. Context variables can be used anywhere a regular variable can be used. Example The following isql script is a trigger that fires after the EMPLOYEE table is updated, and compares an employee’s old and new salary. If there is a change in salary, the trigger inserts an entry in the SALARY_HISTORY table. SET TERM !! ; CREATE TRIGGER SAVE_SALARY_CHANGE FOR EMPLOYEE AFTER UPDATE AS BEGIN IF (OLD.SALARY <> NEW.SALARY) THEN INSERT INTO SALARY_HISTORY (EMP_NO, CHANGE_DATE, UPDATER_ID, OLD_SALARY, PERCENT_CHANGE) VALUES (OLD.EMP_NO, ‘NOW’, USER, OLD.SALARY, (NEW.SALARY - OLD.SALARY) * 100 / OLD.SALARY); END !! SET TERM ; !! See Also NEW context variables For more information about creating triggers, see CREATE TRIGGER on page 80. 174
OUTPUT PARAMETERS Output parameters Used to return values from a stored procedure to the calling application. Available in stored procedures only. Syntax CREATE PROCEDURE name [(param datatype [, param datatype …])] [RETURNS (param datatype [, param datatype …])] Description Output parameters are used to return values from a procedure to the calling application. They are declared in a comma-delimited list in parentheses following the RETURNS keyword in the header of CREATE PROCEDURE. Once declared, they can be used in the procedure body anywhere a variable can appear. They can be of any Firebird datatype except Blob. Arrays of datatypes are also unsupported. If output parameters are declared in a procedure’s header, the procedure must assign them values to return to the calling application. Values can be derived from any valid expression in the procedure. A procedure returns output parameter values to the calling application with a SUSPEND statement. An application receives values of output parameters from a select procedure by using the INTO clause of the SELECT statement. An application receives values of output parameters from an executable procedure by using the RETURNING_VALUES clause. In a SELECT statement that retrieves values from a procedure, the column names must match the names and datatypes of the procedure’s output parameters. In an EXECUTE PROCEDURE statement, the output parameters need not match the names of the procedure’s output parameters, but the datatypes must match. Example The following isql script is a procedure header declares five output parameters, HEAD_DEPT, DEPARTMENT, MNGR_NAME, TITLE, and EMP_CNT: CREATE PROCEDURE ORG_CHART RETURNS (HEAD_DEPT CHAR(25), DEPARTMENT CHAR(25), MNGR_NAME CHAR(20), TITLE CHAR(5), EMP_CNT INTEGER) See Also For more information on declaring output parameters in a procedure, see CREATE PROCEDURE on page 61. LANGUAGE REFERENCE 175
CHAPTER 3 PROCEDURES AND TRIGGERS POST_EVENT Posts an event. Available in triggers and stored procedures. Syntax POST_EVENT ’event_name’ | col; Argument Description ‘event_name’ Name of the event being posted; must be enclosed in quotes Description POST_EVENT posts an event to the event manager. When an event occurs, this statement will notify the event manager, which alerts applications waiting for the named event. Example The following statement posts an event named “new_order”: POST_EVENT ’new_order’; The next statement posts an event based on the current value of a column: POST_EVENT NEW.COMPANY; See Also EVENT INIT, EVENT WAIT For more information on events, see the Embedded SQL Guide. SELECT Retrieves a single row that satisfies the requirements of the search condition. The same as standard singleton SELECT, with some differences in syntax. Available in triggers and stored procedures. <select_expr> = <select_clause> <from_clause> [<where_clause>] [<group_by_clause>] [<having_clause>] [<union_expression>] [<plan_clause>] [<ordering_clause>] <into_clause>; Description In a stored procedure, use the SELECT statement with an INTO clause to retrieve a single row value from the database and assign it to a host variable. The SELECT statement must return at most one row from the database, like a standard singleton SELECT. The INTO clause is required and must be the last clause in the statement. The INTO clause comes at the end of the SELECT statement to allow the use of UNION operators. UNION is not allowed in singleton SELECT statements in embedded SQL. 176
SUSPEND Example The following statement is a standard singleton SELECT statement in an embedded application: EXEC SQL SELECT SUM(BUDGET), AVG(BUDGET) INTO :TOT_BUDGET, :AVG_BUDGET FROM DEPARTMENT WHERE HEAD_DEPT = :HEAD_DEPT To use the above SELECT statement in a procedure, move the INTO clause to the end as follows: SELECT SUM(BUDGET), AVG(BUDGET) FROM DEPARTMENT WHERE HEAD_DEPT = :HEAD_DEPT INTO :TOT_BUDGET, :AVG_BUDGET; See Also FOR SELECT…DO For a complete explanation of the standard SELECT syntax, see SELECT on page 139. SUSPEND Suspends execution of a select procedure until the next FETCH is issued and returns values to the calling application. Available in stored procedures only. Syntax SUSPEND; Description The SUSPEND statement: g Suspends execution of a stored procedure until the application issues the next FETCH. g Returns values of output parameters, if any. A procedure should ensure that all output parameters are assigned values before a SUSPEND. SUSPEND should not be used in an executable procedure. Use EXIT instead to indicate to the reader explicitly that the statement terminates the procedure. LANGUAGE REFERENCE 177
CHAPTER 3 PROCEDURES AND TRIGGERS The following table summarizes the behavior of SUSPEND, EXIT, and END. Procedure type SUSPEND EXIT END Select procedure • Suspends execution of Jumps to final END • Returns control to application procedure until next • Sets SQLCODE to 100 (end of FETCH is issued record stream) • Returns output values Executable procedure • Jumps to final END Jumps to final END • Returns values • Not recommended • Returns control to application TABLE 3.2 SUSPEND, EXIT, and END Note If a SELECT procedure has executable statements following the last SUSPEND in the procedure, all of those statements are executed, even though no more rows are returned to the calling program. The procedure terminates with the final END statement, which sets SQLCODE to 100. The SUSPEND statement also delimits atomic statement blocks in select procedures. If an error occurs in a select procedure—either an SQLCODE error, GDSCODE error, or exception—the statements executed since the last SUSPEND are undone. Statements before the last SUSPEND are never undone, unless the transaction comprising the procedure is rolled back. Example The following procedure, from an isql script, illustrates the use of SUSPEND and EXIT: SET TERM !!; CREATE PROCEDURE P RETURNS (R INTEGER) AS BEGIN R = 0; WHILE (R < 5) DO BEGIN R = R + 1; SUSPEND; IF (R = 3) THEN EXIT; END END; SET TERM ;!! 178
WHEN … DO If this procedure is used as a select procedure in isql, for example, SELECT * FROM P; then it will return values 1, 2, and 3 to the calling application, since the SUSPEND statement returns the current value of r to the calling application until r = 3, when the procedure performs an EXIT and terminates. If the procedure is used as an executable procedure in isql, for example, EXECUTE PROCEDURE P; then it will return 1, since the SUSPEND statement will terminate the procedure and return the current value of r to the calling application. Since SUSPEND should not be used in executable procedures, EXIT would be used instead, indicating that when the statement is encountered, the procedure is exited. See Also EXIT, BEGIN … END WHEN … DO Error-handling statement that performs the statements following DO when the specified error occurs. Available in triggers and stored procedures. Syntax WHEN {<error> [, <error> …] | ANY} DO <compound_statement> <error>= {EXCEPTION exception_name | SQLCODE number | GDSCODE errcode} Argument Description EXCEPTION exception_name The name of an exception already in the database SQLCODE number An SQLCODE error code number GDSCODE errcode An Firebird error code number ANY Keyword that handles any of the above types of errors compound_statement Statement or block executed when any of the specified errors occur. IMPORTANT If used, WHEN must be the last statement in a BEGIN…END block. It should come after SUSPEND, if present. Description Procedures can handle three kinds of errors with a WHEN statement: LANGUAGE REFERENCE 179
CHAPTER 3 PROCEDURES AND TRIGGERS g Exceptions raised by EXCEPTION statements in the current procedure, in a nested procedure, or in a trigger fired as a result of actions by such a procedure. g SQL errors reported in SQLCODE. g Firebird error codes. The WHEN ANY statement handles any of the three types. Handling exceptions Instead of terminating when an exception occurs, a procedure can respond to and perhaps correct the error condition by handling the exception. When an exception is raised, it: g Terminates execution of the BEGIN … END block containing the exception and undoes any actions performed in the block. g Backs out one level to the next BEGIN … END block and seeks an exception-handling (WHEN) statement, and continues backing out levels until one is found. If no WHEN statement is found, the procedure is terminated and all its actions are undone. g Performs the ensuing statement or block of statements specified after WHEN, if found. g Returns program control to the block or statement in the procedure following the WHEN statement. Note An exception that is handled with WHEN does not return an error message. Handling SQL errors Procedures can also handle error numbers returned in SQLCODE. After each SQL statement executes, SQLCODE contains a status code indicating the success or failure of the statement. It can also contain a warning status, such as when there are no more rows to retrieve in a FOR SELECT loop. 180
WHEN … DO Handling Firebird error codes Procedures can also handle Firebird error codes. For example, suppose a statement in a procedure attempts to update a row already updated by another transaction, but not yet committed. In this case, the procedure might receive an Firebird error code, isc_lock_conflict. Perhaps if the procedure retries its update, the other transaction may have rolled back its changes and released its locks. By using a WHEN GDSCODE statement, the procedure can handle lock conflict errors and retry its operation. Example For example, if a procedure attempts to insert a duplicate value into a column defined as a PRIMARY KEY, Firebird will return SQLCODE -803. This error can be handled in a procedure with the following statement: WHEN SQLCODE -803 DO BEGIN . . . For example, the following procedure, from an isql script, includes a WHEN statement to handle errors that may occur as the procedure runs. If an error occurs and SQLCODE is as expected, the procedure continues with the new value of B. If not, the procedure cannot handle the error, and rolls back all actions of the procedure, returning the active SQLCODE. SET TERM !!; CREATE PROCEDURE NUMBERPROC (A INTEGER) RETURNS (B INTEGER) AS BEGIN B = 0; BEGIN UPDATE R SET F1 = F1 + :A; UPDATE R SET F2 = F2 * F2; UPDATE R SET F1 = F1 + :A; WHEN SQLCODE -803 DO B = 1; END EXIT; END!! SET TERM; !! See Also EXCEPTION For more information about Firebird error codes and SQLCODE values, see Chapter 6, “Error Codes and Messages.” LANGUAGE REFERENCE 181
CHAPTER 3 PROCEDURES AND TRIGGERS WHILE … DO Performs the statement or block following DO as long as the specified condition is TRUE. Available in triggers and stored procedures. Syntax WHILE (<condition>) DO <compound_statement> Argument Description condition Boolean expression tested before each execution of the statement or block following DO compound_statement Statement or block executed as long as condition is TRUE Description WHILE … DO is a looping statement that repeats a statement or block of statements as long as a condition is true. The condition is tested at the start of each loop. Example The following procedure, from an isql script, uses a WHILE … DO loop to compute the sum of all integers from one up to the input parameter: SET TERM !!; CREATE PROCEDURE SUM_INT (I INTEGER) RETURNS (S INTEGER) AS BEGIN S = 0; WHILE (I > 0) DO BEGIN S = S + I; I = I - 1; END END!! SET TERM ; !! If this procedure is called from isql with the command: EXECUTE PROCEDURE SUM_INT 4; then the results will be: S ========== 10 See Also IF…THEN … ELSE, FOR SELECT…DO 182
CHAPTER 4 Keywords Chapter 4
Reserved words are part of the Firebird SQL language. They cannot be used as identifiers (e.g. as table or procedure names), except when enclosed in double quotes in Dialect 3. However, you should avoid this unless you have a compelling reason.

Keywords are also part of the language. They have a special meaning when used in the proper context, but they are not reserved for Firebird's own and exclusive use. You can use them as identifiers without double-quoting.
Reserved words
Keywords
g Part of statements g Used as statements g Names of standard data structures or datatypes
CHAPTER 5 User-Defined Functions Chapter 5 User-defined functions (UDFs) are host-language programs for performing frequently needed tasks, supplementing built-in SQL functions such as MIN() and MAX(). UDFs are extensions to the Firebird server and execute as part of the server process. A brief overview UDFs are discussed in detail in the “Working with UDFs” chapter in the Developer’s Guide for details on writing and using UDFs. This section provides only an introduction. Creating a UDF is a three-step process: 1. Write and compile the function in a programming language such as C or Delphi. 2. Add it to a dynamically-linked library. 3. Use DECLARE EXTERNAL FUNCTION to declare each individual UDF to each database in which you need to use it. Beginning with Firebird 6, the rules for placing a library module have changed. It must meet one of the following criteria: · It is located in ib_install_dir/UDF LANGUAGE REFERENCE 189
CHAPTER 5 USER-DEFINED FUNCTIONS · The complete pathname to the directory, including a drive letter in the case of a Windows server, is listed in the Firebird configuration file. Note that it is no longer sufficient to state a complete path name to the module in DECLARE EXTERNAL FUNCTION. These changes have been implemented for security reasons. UDF library Firebird provides a number of often-needed functions in the form of a UDF library, which is named ib_udf.dll on Windows platforms and ib_udf on UNIX platforms. This library is is interbase_home/lib. These UDFs are all implemented using the standard C library. This section describes each UDF and provides its declaration. There is a script, ib_udf.sql, in the interbase_home/examples/udf subdirectory that declares all of the functions listed below. If you want to declare only a subset of these, copy and edit the script file. IMPORTANT Several of these UDFs must be called using the new FREE_IT keyword if—and only if—they are written in thread-safe form, using malloc to allocate dynamic memory. Note When trigonometric functions are passed inputs that are out of bounds, they return zero rather than NaN. abs Returns the absolute value of a number. DECLARE EXTERNAL FUNCTION ABS DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_abs’ MODULE_NAME ’ib_udf’; acos Returns the arccosine of a number between −1 and 1; if the number is out of bounds it returns zero. DECLARE EXTERNAL FUNCTION ACOS DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_acos’ MODULE_NAME ’ib_udf’; 190
UDF LIBRARY ascii_char Returns the ASCII character corresponding to the value passed in. DECLARE EXTERNAL FUNCTION ASCII_CHAR INTEGER RETURNS CHAR(1) ENTRY_POINT ’IB_UDF_ascii_char’ MODULE_NAME ’ib_udf’; ascii_val Returns the ASCII value of the character passed in. DECLARE EXTERNAL FUNCTION ASCII_VAL CHAR(1) RETURNS INTEGER BY VALUE ENTRY_POINT ’IB_UDF_ascii_val’ MODULE_NAME ’ib_udf’; asin Returns the arcsin of a number between −1 and 1; returns zero if the number is out of range. DECLARE EXTERNAL FUNCTION ASIN DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_asin’ MODULE_NAME ’ib_udf’; atan Returns the arctangent of the input value. DECLARE EXTERNAL FUNCTION ATAN DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_atan’ MODULE_NAME ’ib_udf’; LANGUAGE REFERENCE 191
CHAPTER 5 USER-DEFINED FUNCTIONS atan2 Returns the arctangent of the first parameter divided by the second parameter. DECLARE EXTERNAL FUNCTION ATAN2 DOUBLE PRECISION, DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_atan2’ MODULE_NAME ’ib_udf’; bin_and Returns the result of a binary AND operation performed on the two input values. DECLARE EXTERNAL FUNCTION BIN_AND INTEGER, INTEGER RETURNS INTEGER BY VALUE ENTRY_POINT ’IB_UDF_bin_and’ MODULE_NAME ’ib_udf’; bin_or Returns the result of a binary OR operation performed on the two input values. DECLARE EXTERNAL FUNCTION BIN_OR INTEGER, INTEGER RETURNS INTEGER BY VALUE ENTRY_POINT ’IB_UDF_bin_or’ MODULE_NAME ’ib_udf’; bin_xor Returns the result of a binary XOR operation performed on the two input values. DECLARE EXTERNAL FUNCTION BIN_XOR INTEGER, INTEGER RETURNS INTEGER BY VALUE ENTRY_POINT ’IB_UDF_bin_xor’ MODULE_NAME ’ib_udf’; 192
UDF LIBRARY ceiling Returns a double value representing the smallest integer that is greater than or equal to the input value. DECLARE EXTERNAL FUNCTION CEILING DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_ceiling’ MODULE_NAME ’ib_udf’; cos Returns the cosine of x. If x is greater than or equal to 263, or less than or equal to −263, there is a loss of significance in the result of the call, and the function generates a _TLOSS error and returns a zero. DECLARE EXTERNAL FUNCTION COS DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_cos’ MODULE_NAME ’ib_udf’; cosh Returns the hyperbolic cosine of x. If x is greater than or equal to 263, or less than or equal to −263, there is a loss of significance in the result of the call, and the function generates a _TLOSS error and returns a zero. DECLARE EXTERNAL FUNCTION COSH DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_cosh’ MODULE_NAME ’ib_udf’; cot Returns 1 over the tangent of the input value. DECLARE EXTERNAL FUNCTION COT DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_cot’ MODULE_NAME ’ib_udf’; LANGUAGE REFERENCE 193
CHAPTER 5 USER-DEFINED FUNCTIONS div Divides the two inputs and returns the quotient. DECLARE EXTERNAL FUNCTION DIV INTEGER, INTEGER RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_div’ MODULE_NAME ’ib_udf’; floor Returns a floating-point value representing the largest integer that is less than or equal to x. DECLARE EXTERNAL FUNCTION FLOOR DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_floor’ MODULE_NAME ’ib_udf’; ln Returns the natural log of a number. DECLARE EXTERNAL FUNCTION LN DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_ln’ MODULE_NAME ’ib_udf’; log LOG(x,y) returns the logarithm base x of y. DECLARE EXTERNAL FUNCTION LOG DOUBLE PRECISION, DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_log’ MODULE_NAME ’ib_udf’; 194
UDF LIBRARY log10 Returns the logarithm base 10 of the input value. DECLARE EXTERNAL FUNCTION LOG10 DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_log10’ MODULE_NAME ’ib_udf’; lower Returns the input string as lowercase characters. This function works only with ASCII characters. Note This function can receive and return up to 32,767 characters, the limit on an Firebird character string. DECLARE EXTERNAL FUNCTION lower CSTRING(80) RETURNS CSTRING(80) FREE_IT ENTRY_POINT ’IB_UDF_lower’ MODULE_NAME ’ib_udf’; ltrim Removes leading spaces from the input string. Note This function can receive and return up to 32,767 characters, the limit on an Firebird character string. DECLARE EXTERNAL FUNCTION LTRIM CSTRING(80) RETURNS CSTRING(80) FREE_IT ENTRY_POINT ’IB_UDF_ltrim’ MODULE_NAME ’ib_udf’; mod Divides the two input parameters and returns the remainder. DECLARE EXTERNAL FUNCTION MOD INTEGER, INTEGER RETURNS DOUBLE PRECISION BY VALUE LANGUAGE REFERENCE 195
CHAPTER 5 USER-DEFINED FUNCTIONS ENTRY_POINT ’IB_UDF_mod’ MODULE_NAME ’ib_udf’; pi Returns the value of pi = 3.14159... DECLARE EXTERNAL FUNCTION PI RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_pi’ MODULE_NAME ’ib_udf’; rand Returns a random number between 0 and 1. The current time is used to seed the random number generator. DECLARE EXTERNAL FUNCTION rand RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_rand’ MODULE_NAME ’ib_udf’; rtrim Removes trailing spaces from the input string. Note This function can receive and return up to 32,767 characters, the limit on an Firebird character string. DECLARE EXTERNAL FUNCTION RTRIM CSTRING(80) RETURNS CSTRING(80) FREE_IT ENTRY_POINT ’IB_UDF_rtrim’ MODULE_NAME ’ib_udf’; sign Returns 1, 0, or −1 depending on whether the input value is positive, zero or negative, respectively. DECLARE EXTERNAL FUNCTION SIGN DOUBLE PRECISION RETURNS INTEGER BY VALUE ENTRY_POINT ’IB_UDF_sign’ MODULE_NAME ’ib_udf’; 196
UDF LIBRARY sin Returns the sine of x. If x is greater than or equal to 263, or less than or equal to −263, there is a loss of significance in the result of the call, and the function generates a _TLOSS error and returns a zero. DECLARE EXTERNAL FUNCTION SIN DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_sin’ MODULE_NAME ’ib_udf’; sinh Returns the hyperbolic sine of x. If x is greater than or equal to 263, or less than or equal to −263, there is a loss of significance in the result of the call, and the function generates a _TLOSS error and returns a zero. DECLARE EXTERNAL FUNCTION SINH DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_sinh’ MODULE_NAME ’ib_udf’; sqrt Returns the square root of a number. DECLARE EXTERNAL FUNCTION SQRT DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_sqrt’ MODULE_NAME ’ib_udf’; strlen Returns the length of a the input string. DECLARE EXTERNAL FUNCTION STRLEN CSTRING(32767) RETURNS INTEGER BY VALUE ENTRY_POINT ’IB_UDF_strlen’ MODULE_NAME ’ib_udf’; LANGUAGE REFERENCE 197
CHAPTER 5 USER-DEFINED FUNCTIONS substr SUBSTR(s,m,n) returns the substring of s starting at position m and ending at position n. Note This function can receive and return up to 32,767 characters, the limit on an Firebird character string. DECLARE EXTERNAL FUNCTION SUBSTR CSTRING(80), SMALLINT, SMALLINT RETURNS CSTRING(80) FREE_IT ENTRY_POINT ’IB_UDF_substr’ MODULE_NAME ’ib_udf’; tan Returns the tangent of x. If x is greater than or equal to 263, or less than or equal to −263, there is a loss of significance in the result of the call, and the function generates a _TLOSS error and returns a zero. DECLARE EXTERNAL FUNCTION TAN DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_tan’ MODULE_NAME ’ib_udf’; tanh Returns the tangent of x. If x is greater than or equal to 263, or less than or equal to −263, there is a loss of significance in the result of the call, and the function generates a _TLOSS error and returns a zero. DECLARE EXTERNAL FUNCTION TANH DOUBLE PRECISION RETURNS DOUBLE PRECISION BY VALUE ENTRY_POINT ’IB_UDF_tanh’ MODULE_NAME ’ib_udf’; 198
CHAPTER 6 Error Codes and Messages Chapter 6 This chapter summarizes Firebird error-handling options and error codes. Tables in this chapter list SQLCODE and Firebird error codes and messages for embedded SQL, dynamic SQL (DSQL), and interactive SQL (isql). For a detailed discussion of error handling, see the Embedded SQL Guide. Error sources Run-time errors occur at points of user input or program output. When you run a program or use isql, the following types of errors may occur: Error type Description Action Database error Database errors can result from If you encounter one of these messages: any one of many problems, such as • Check any messages conversion errors, arithmetic • Check the file name or path name and try again exceptions, and validation errors Bugcheck or Bugchecks reflect software If you encounter a bugcheck, execute a traceback and save internal error problems you should report the output; submit output and script along with a copy of the database to Firebird Software Corp. LANGUAGE REFERENCE 199
CHAPTER 6 ERROR CODES AND MESSAGES Error reporting and handling For reporting and dealing with errors, Firebird utilizes the SQLCODE variable and Firebird codes returned in the status array. Every executable SQL statement sets the SQLCODE variable, which can serve as a status indicator. During preprocessing, gpre declares this variable automatically. An application can test for and use the SQLCODE variable in one of three ways: g Use the WHENEVER statement to check the value of SQLCODE and direct the program to branch to error-handling routines coded in the application. g Test for SQLCODE directly. g Combine WHENEVER and direct SQLCODE testing. For SQL programs that must be portable between Firebird and other database management systems, limit error-handling routines to one of these methods. The Firebird status array displays information about errors that supplements SQLCODE messages. Firebird applications can check both the SQLCODE message and the message returned in the status array. Trapping errors with WHENEVER The WHENEVER statement traps SQL errors and warnings. WHENEVER tests SQLCODE return values and branches to appropriate error-handling routines in the application. Error routines can range from: g Simple reporting of errors and transaction rollback, or a prompt to the user to reenter a query or data. g More sophisticated routines that react to many possible error conditions in predictable ways. WHENEVER helps limit the size of an application, since it can call on a single suite of routines for handling errors and warnings. 200
ERROR REPORTING AND HANDLING Checking SQLCODE value directly Applications can test directly for a particular SQLCODE after each SQL statement. If that SQLCODE occurs, the program can branch to a specific routine. To handle specific error situations, combine checking for SQLCODE with general WHENEVER statements. These steps outline the procedure, which is described in detail in the Embedded SQL Guide: 1. Override the WHENEVER branching by inserting a WHENEVER SQLERROR CONTINUE statement. The program now ignores SQLCODE. 2. Use an SQLCODE-checking statement to check for a particular SQLCODE and direct the program to an alternative procedure. 3. To return to WHENEVER branching, insert a new WHENEVER statement. Where portability is not an issue, additional information may be available in the Firebird status array. Firebird status array Since each SQLCODE value can result from more than one type of error, the Firebird status array (isc_status) provides additional messages that enable further inquiry into SQLCODE errors. gpre automatically declares isc_status, an array of twenty 32-bit integers, for all Firebird applications during preprocessing. When an error occurs, the status array is loaded with Firebird error codes, message string addresses, and sometimes other numeric, interpretive, platform-specific error data. This chapter lists all status array codes in “SQLCODE error codes and messages” on page 203. To see the codes online, display the ibase.h file. The location of this file is system-specific. 4 Access to status array messages Firebird provides the following library functions tofor retrieving and printing status array codes and messages. ISC_PRINT_SQLERROR( ) When SQLCODE < 0, this function prints the returned SQLCODE value, the corresponding SQL error message, and any additional Firebird error messages in the status array to the screen. Use within an error-handling routine. LANGUAGE REFERENCE 201
CHAPTER 6 ERROR CODES AND MESSAGES Syntax isc_print_sqlerror (short SQLCODE, ISC_STATUS *status_vector); ISC_SQL_INTERPRETE( ) This function retrieves an SQL error message and stores it in a user-supplied buffer for later printing, manipulation, or display. Allow a buffer length of 256 bytes to hold the message. Use when building error display routines or if you are using a windowing system that does not permit direct screen writes. Do not use this function when SQLCODE > 0. Syntax isc_sql_interprete(short SQLCODE, char *buffer, short length); 4 Responding to error codes After any error occurs, you have the following options: ignore the error, log the error and continue processing, roll back the transaction and try again, or roll back the transaction and quit the application. For the following errors, it is recommended that you roll back the current transaction and try the operation again: Status array code Action to take isc_convert_error Conversion error: A conversion between datatypes failed; correct the input and retry the operation isc_deadlock Deadlock: Transaction conflicted with another transaction; wait and try again isc_integ_fail Integrity check: Operation failed due to a trigger; examine the abort code, fix the error, and try again isc_lock_conflict Lock conflict: Transaction unable to obtain the locks it needed; wait and try again isc_no_dup Duplicate index entry: Attempt to add a duplicate field; correct field with duplicate and try again isc_not_valid Validation error: Row did not pass validation test; correct invalid row and try again TABLE 6.1 Status array codes that require rollback and retry 202
SQLCODE ERROR CODES AND MESSAGES For more information The following table is a guide to further information on planning and programming error-handling routines. Topic To find… See… SQLCODE and error Complete discussion and programming Embedded SQL Guide handling instructions List of SQLCODEs SQLCODEs and associated messages for embedded This chapter: “SQLCODE Codes and SQL, DSQL, isql Messages” WHENEVER syntax Usage and syntax Chapter 2: “SQL Statement Definitions” Programming Using and programming error-handling routines Embedded SQL Guide WHENEVER Firebird status array Complete programming instructions Embedded SQL Guide and functions List of status array Status array error codes and associated messages This chapter: “Firebird Status Array Error codes for embedded SQL, DSQL, isql Codes for SQL” TABLE 6.2 Where to find error-handling topics SQLCODE error codes and messages This section lists SQLCODE error codes and associated messages in the following tables: g SQLCODE error messages summary g SQLCODE codes and messages LANGUAGE REFERENCE 203
CHAPTER 6 ERROR CODES AND MESSAGES SQLCODE error messages summary This table summarizes the types of messages SQLCODE can pass to a program: SQLCODE Message Meaning <0 SQLERROR Error: The statement did not complete; table B-4 lists SQLCODE error numbers and messages. 0 SUCCESS Successful completion +1–99 SQLWARNING System warning or informational message +100 NOT FOUND No qualifying records found; end of file TABLE 6.3 SQLCODE and messages summary SQLCODE codes and messages The following table lists SQLCODEs and associated messages for SQL and DSQL. Some SQLCODE values have more than one text message associated with them. In these cases, Firebird returns the most relevant string message for the error that occurred. When code messages include the name of a database object or object type, the name is represented by a code in the SQLCODE Text column: g <string>: String value, such as the name of a database object or object type. g <long>: Long integer value, such as the identification number or code of a database object or object type. g <digit>: Integer value, such as the identification number or code of a database object or object type. 204
SQLCODE ERROR CODES AND MESSAGES g The Firebird number in the right-hand column is the actual error number returned in the error status vector. You can use Firebird error-handling functions to report messages based on these numbers instead of SQL code, but doing so results in non-portable SQL programs. Firebird SQLCODE SQLCODE text number 101 Segment buffer length shorter than expected 335544366L 100 No match for first value expression 335544338L 100 Invalid database key 335544354L 100 Attempted retrieval of more segments than exist 335544367L 100 Attempt to fetch past the last record in a record stream 335544374L -84 Table/procedure has non-SQL security class defined 335544554L -84 Column has non-SQL security class defined 335544555L -84 Procedure <string> does not return any values 335544668L -103 Datatype for constant unknown 335544571L -104 Invalid request BLR at offset <long> 335544343L -104 BLR syntax error: expected <string> at offset <long>, 335544390L encountered <long> -104 Context already in use (BLR error) 335544425L -104 Context not defined (BLR error) 335544426L -104 Bad parameter number 335544429L -104 335544440L -104 Invalid slice description language at offset <long> 335544456L -104 Invalid command 335544570L -104 Internal error 335544579L -104 Option specified more than once 335544590L TABLE 6.4 SQLCODE codes and messages LANGUAGE REFERENCE 205
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -104 Unknown transaction option 335544591L -104 Invalid array reference 335544592L -104 Token unknown—line <long>, char <long> 335544634L -104 Unexpected end of command 335544608L -104 Token unknown 335544612L -150 Attempted update of read-only table 335544360L -150 Cannot update read-only view <string> 335544362L -150 Not updatable 335544446L -150 Cannot define constraints on views 335544546L -151 Attempted update of read-only column 335544359L -155 <string> is not a valid base table of the specified view 335544658L -157 Must specify column name for view select expression 335544598L -158 Number of columns does not match select list 335544599L -162 Dbkey not available for multi-table views 335544685L -170 Parameter mismatch for procedure <string> 335544512L -170 External functions cannot have more than10 parameters 335544619L -171 Function <string> could not be matched 335544439L -171 Column not array or invalid dimensions (expected <long>, encountered 335544458L<long>) -171 Return mode by value not allowed for this datatype 335544618L -172 Function <string> is not defined 335544438L -204 Generator <string> is not defined 335544463L -204 Reference to invalid stream number 335544502L TABLE 6.4 SQLCODE codes and messages (continued) 206
SQLCODE ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -204 CHARACTER SET <string> is not defined 335544509L -204 Procedure <string> is not defined 335544511L -204 Status code <string> unknown 335544515L -204 Exception <string> not defined 335544516L -204 Name of Referential Constraint not defined in constraints table. 335544532L -204 Could not find table/procedure for GRANT 335544551L -204 Implementation of text subtype <digit> not located. 335544568L -204 Datatype unknown 335544573L -204 Table unknown 335544580L -204 Procedure unknown 335544581L -204 COLLATION <string> is not defined 335544588L -204 COLLATION <string> is not valid for specified CHARACTER SET 335544589L -204 Trigger unknown 335544595L -204 Alias <string> conflicts with an alias in the same statement 335544620L -204 Alias <string> conflicts with a procedure in the same statement 335544621L -204 Alias <string> conflicts with a table in the same statement 335544622L -204 There is no alias or table named <string> at this scope level 335544635L -204 There is no index <string> for table <string> 335544636L -204 Invalid use of CHARACTER SET or COLLATE 335544640L -204 BLOB SUB_TYPE <string> is not defined 335544662L -205 Column <string> is not defined in table <string> 335544396L -205 Could not find column for GRANT 335544552L -206 Column unknown 335544578L TABLE 6.4 SQLCODE codes and messages (continued) LANGUAGE REFERENCE 207
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -206 Column is not a Blob 335544587L -206 Subselect illegal in this context 335544596L -208 Invalid ORDER BY clause 335544617L -219 Table <string> is not defined 335544395L -239 Cache length too small 335544691L -260 Cache redefined 335544690L -281 Table <string> is not referenced in plan 335544637L -282 Table <string> is referenced more than once in plan; use aliases to 335544638L distinguish -282 The table <string> is referenced twice; use aliases to differentiate 335544643L -282 Table <string> is referenced twice in view; use an alias to distinguish 335544659L -282 View <string> has more than one base table; use aliases to distinguish 335544660L -283 Table <string> is referenced in the plan but not the from list 335544639L -284 Index <string> cannot be used in the specified plan 335544642L -291 Column used in a PRIMARY/UNIQUE constraint must be NOT NULL. 335544531L -292 Cannot update constraints (RDB$REF_CONSTRAINTS). 335544534L -293 Cannot update constraints (RDB$CHECK_CONSTRAINTS). 335544535L -294 Cannot delete CHECK constraint entry (RDB$CHECK_CONSTRAINTS) 335544536L -295 Cannot update constraints (RDB$RELATION_CONSTRAINTS). 335544545L -296 Internal isc software consistency check (invalid RDB$CONSTRAINT_TYPE) 335544547L -297 Operation violates CHECK constraint <string> on view or table 335544558L -313 Count of column list and variable list do not match 335544669L -314 Cannot transliterate character between character sets 335544565L TABLE 6.4 SQLCODE codes and messages (continued) 208
SQLCODE ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -401 Invalid comparison operator for find operation 335544647L -402 Attempted invalid operation on a Blob 335544368L -402 Blob and array datatypes are not supported for <string> operation 335544414L -402 Data operation not supported 335544427L -406 Subscript out of bounds 335544457L -407 Null segment of UNIQUE KEY 335544435L -413 Conversion error from string “<string>” 335544334L -413 Filter not found to convert type <long> to type <long> 335544454L -501 Invalid request handle 335544327L -501 Attempt to reclose a closed cursor 335544577L -502 Declared cursor already exists 335544574L -502 Attempt to reopen an open cursor 335544576L -504 Cursor unknown 335544572L -508 No current record for fetch operation 335544348L -510 Cursor not updatable 335544575L -518 Request unknown 335544582L -519 The PREPARE statement identifies a prepare statement with an open 335544688L cursor -530 Violation of FOREIGN KEY constraint: “<string>” 335544466L -530 Cannot prepare a CREATE DATABASE/SCHEMA statement 335544597L -532 Transaction marked invalid by I/O error 335544469L -551 No permission for <string> access to <string> <string> 335544352L -552 Only the owner of a table can reassign ownership 335544550L TABLE 6.4 SQLCODE codes and messages (continued) LANGUAGE REFERENCE 209
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -552 User does not have GRANT privileges for operation 335544553L -553 Cannot modify an existing user privilege 335544529L -595 The current position is on a crack 335544645L -596 Illegal operation when at beginning of stream 335544644L -597 Preceding file did not specify length, so <string> must include starting 335544632Lpage number -598 Shadow number must be a positive integer 335544633L -599 Gen.c: node not supported 335544607L -600 A node name is not permitted in a secondary, shadow, cache or log file 335544625Lname -600 Sort error: corruption in data structure 335544680L -601 Database or file exists 335544646L -604 Array declared with too many dimensions 335544593L -604 Illegal array dimension range 335544594L -605 Inappropriate self-reference of column 335544682L -607 Unsuccessful metadata update 335544351L -607 Cannot modify or erase a system trigger 335544549L -607 Array/Blob/DATE/TIME/TIMESTAMP datatypes not allowed in arithmetic 335544657L -615 Lock on table <string> conflicts with existing lock 335544475L -615 Requested record lock conflicts with existing lock 335544476L -615 Refresh range number <long> already in use 335544507L -616 Cannot delete PRIMARY KEY being used in FOREIGN KEY definition. 335544530L -616 Cannot delete index used by an integrity constraint 335544539L -616 Cannot modify index used by an integrity constraint 335544540L TABLE 6.4 SQLCODE codes and messages (continued) 210
SQLCODE ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -616 Cannot delete trigger used by a CHECK Constraint 335544541L -616 Cannot delete column being used in an integrity constraint. 335544543L -616 There are <long> dependencies 335544630L -616 Last column in a table cannot be deleted 335544674L -617 Cannot update trigger used by a CHECK Constraint 335544542L -617 Cannot rename column being used in an integrity constraint. 335544544L -618 Cannot delete index segment used by an integrity constraint 335544537L -618 Cannot update index segment used by an integrity constraint 335544538L -625 Validation error for column <string>, value “<string>” 335544347L -637 Duplicate specification of <string> not supported 335544664L -660 Non-existent PRIMARY or UNIQUE KEY specified for FOREIGN KEY 335544533L -660 Cannot create index <string> 335544628L -663 Segment count of 0 defined for index <string> 335544624L -663 Too many keys defined for index <string> 335544631L -663 Too few key columns found for index <string> (incorrect column 335544672L name?) -664 key size exceeds implementation restriction for index “<string>” 335544434L -677 <string> extension error 335544445L -685 Invalid Blob type for operation 335544465L -685 Attempt to index Blob column in index <string> 335544670L -685 Attempt to index array column in index <string> 335544671L -689 Page <long> is of wrong type (expected <long>, found <long>) 335544403L -689 Wrong page type 335544650L TABLE 6.4 SQLCODE codes and messages (continued) LANGUAGE REFERENCE 211
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -690 Segments not allowed in expression index <string> 335544679L -691 New record size of <long> bytes is too big 335544681L -692 Maximum indexes per table (<digit>) exceeded 335544477L -693 Too many concurrent executions of the same request 335544663L -694 Cannot access column <string> in view <string> 335544684L -802 Arithmetic exception, numeric overflow, or string truncation 335544321L -803 Attempt to store duplicate value (visible to active transactions) in 335544349L unique index “<string>” -803 Violation of PRIMARY or UNIQUE KEY constraint: “<string>” 335544665L -804 Wrong number of arguments on call 335544380L -804 SQLDA missing or incorrect version, or incorrect number/type of variables 335544583L -804 Count of columns not equal count of values 335544584L -804 Function unknown 335544586L -806 Only simple column names permitted for VIEW WITH CHECK OPTION 335544600L -807 No where clause for VIEW WITH CHECK OPTION 335544601L -808 Only one table allowed for VIEW WITH CHECK OPTION 335544602L -809 DISTINCT, GROUP or HAVING not permitted for VIEW WITH CHECK OPTION 335544603L -810 No subqueries permitted for VIEW WITH CHECK OPTION 335544605L -811 Multiple rows in singleton select 335544652L -816 External file could not be opened for output 335544651L -817 Attempted update during read-only transaction 335544361L -817 Attempted write to read-only Blob 335544371L -817 Operation not supported 335544444L TABLE 6.4 SQLCODE codes and messages (continued) 212
SQLCODE ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -820 Metadata is obsolete 335544356L -820 Unsupported on-disk structure for file <string>; found <long>, support 335544379L<long> -820 Wrong DYN version 335544437L -820 Minor version too high found <long> expected <long> 335544467L -823 Invalid bookmark handle 335544473L -824 Invalid lock level <digit> 335544474L -825 Invalid lock handle 335544519L -826 Invalid statement handle 335544585L -827 Invalid direction for find operation 335544655L -828 Invalid key position 335544678L -829 Invalid column reference 335544616L -830 Column used with aggregate 335544615L -831 Attempt to define a second PRIMARY KEY for the same table 335544548L -832 FOREIGN KEY column count does not match PRIMARY KEY 335544604L -833 Expression evaluation not supported 335544606L -834 Refresh range number <long> not found 335544508L -835 Bad checksum 335544649L -836 Exception <digit> 335544517L -837 Restart shared cache manager 335544518L -838 Database <string> shutdown in <digit> seconds 335544560L -839 journal file wrong format 335544686L -840 Intermediate journal file full 335544687L TABLE 6.4 SQLCODE codes and messages (continued) LANGUAGE REFERENCE 213
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -841 Too many versions 335544677L -842 Precision should be greater than 0 335544697L -842 Scale cannot be greater than precision 335544698L -842 Short integer expected 335544699L -842 Long integer expected 335544700L -842 Unsigned short integer expected 335544701L -901 Invalid database key 335544322L -901 Unrecognized database parameter block 335544326L -901 Invalid Blob handle 335544328L -901 Invalid Blob ID 335544329L -901 Invalid parameter in transaction parameter block 335544330L -901 Invalid format for transaction parameter block 335544331L -901 Invalid transaction handle (expecting explicit transaction start) 335544332L -901 Attempt to start more than <long> transactions 335544337L -901 Information type inappropriate for object specified 335544339L -901 No information of this type available for object specified 335544340L -901 Unknown information item 335544341L -901 Action cancelled by trigger (<long>) to preserve data integrity 335544342L -901 Lock conflict on no wait transaction 335544345L -901 Program attempted to exit without finishing database 335544350L -901 Transaction is not in limbo 335544353L -901 Blob was not closed 335544355L -901 Cannot disconnect database with open transactions (<long> active) 335544357L TABLE 6.4 SQLCODE codes and messages (continued) 214
SQLCODE ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -901 Message length error (encountered <long>, expected <long>) 335544358L -901 No transaction for request 335544363L -901 Request synchronization error 335544364L -901 Request referenced an unavailable database 335544365L -901 Attempted read of a new, open Blob 335544369L -901 Attempted action on blob outside transaction 335544370L -901 Attempted reference to Blob in unavailable database 335544372L -901 Table <string> was omitted from the transaction reserving list 335544376L -901 Request includes a DSRI extension not supported in this 335544377L implementation -901 Feature is not supported 335544378L -901 <string> 335544382L -901 Unrecoverable conflict with limbo transaction <long> 335544383L -901 Internal error 335544392L -901 Database handle not zero 335544407L -901 Transaction handle not zero 335544408L -901 Transaction in limbo 335544418L -901 Transaction not in limbo 335544419L -901 Transaction outstanding 335544420L -901 Undefined message number 335544428L -901 Blocking signal has been received 335544431L -901 Database system cannot read argument <long> 335544442L -901 Database system cannot write argument <long> 335544443L TABLE 6.4 SQLCODE codes and messages (continued) LANGUAGE REFERENCE 215
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -901 <string> 335544450L -901 Transaction <long> is <string> 335544468L -901 Invalid statement handle 335544485L -901 Lock time-out on wait transaction 335544510L -901 Invalid service handle 335544559L -901 Wrong version of service parameter block 335544561L -901 Unrecognized service parameter block 335544562L -901 Service <string> is not defined 335544563L -901 INDEX <string> 335544609L -901 EXCEPTION <string> 335544610L -901 Column <string> 335544611L -901 Union not supported 335544613L -901 Unsupported DSQL construct 335544614L -901 Illegal use of keyword VALUE 335544623L -901 Table <string> 335544626L -901 Procedure <string> 335544627L -901 Specified domain or source column does not exist 335544641L -901 Variable <string> conflicts with parameter in same procedure 335544656L -901 Server version too old to support all CREATE DATABASE options 335544666L -901 Cannot delete 335544673L -901 Sort error 335544675L -902 Internal isc software consistency check (<string>) 335544333L -902 Database file appears corrupt (<string>) 335544335L TABLE 6.4 SQLCODE codes and messages (continued) 216
SQLCODE ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -902 I/O error during “<string>” operation for file “<string>” 335544344L -902 Corrupt system table 335544346L -902 Operating system directive <string> failed 335544373L -902 Internal error 335544384L -902 Internal error 335544385L -902 Internal error 335544387L -902 Block size exceeds implementation restriction 335544388L -902 Incompatible version of on-disk structure 335544394L -902 Internal error 335544397L -902 Internal error 335544398L -902 Internal error 335544399L -902 Internal error 335544400L -902 Internal error 335544401L -902 Internal error 335544402L -902 Database corrupted 335544404L -902 Checksum error on database page <long> 335544405L -902 Index is broken 335544406L -902 Transaction--request mismatch (synchronization error) 335544409L -902 Bad handle count 335544410L -902 Wrong version of transaction parameter block 335544411L -902 Unsupported BLR version (expected <long>, encountered <long>) 335544412L -902 Wrong version of database parameter block 335544413L -902 Database corrupted 335544415L TABLE 6.4 SQLCODE codes and messages (continued) LANGUAGE REFERENCE 217
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -902 Internal error 335544416L -902 Internal error 335544417L -902 Internal error 335544422L -902 Internal error 335544423L -902 Lock manager error 335544432L -902 SQL error code = <long> 335544436L -902 335544448L -902 335544449L -902 Cache buffer for page <long> invalid 335544470L -902 There is no index in table <string> with id <digit> 335544471L -902 Your user name and password are not defined. Ask your database 335544472L administrator to set up an Firebird login. -902 Enable journal for database before starting online dump 335544478L -902 Online dump failure. Retry dump 335544479L -902 An online dump is already in progress 335544480L -902 No more disk/tape space. Cannot continue online dump 335544481L -902 Maximum number of online dump files that can be specified is 16 335544483L -902 Database <string> shutdown in progress 335544506L -902 Long-term journaling already enabled 335544520L -902 Database <string> shutdown 335544528L -902 Database shutdown unsuccessful 335544557L -902 Cannot attach to password database 335544653L -902 Cannot start transaction for password database 335544654L TABLE 6.4 SQLCODE codes and messages (continued) 218
SQLCODE ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -902 Long-term journaling not enabled 335544564L -902 Dynamic SQL Error 335544569L -904 Invalid database handle (no active connection) 335544324L -904 Unavailable database 335544375L -904 Implementation limit exceeded 335544381L -904 Too many requests 335544386L -904 Buffer exhausted 335544389L -904 Buffer in use 335544391L -904 Request in use 335544393L -904 No lock manager available 335544424L -904 Unable to allocate memory from operating system 335544430L -904 Update conflicts with concurrent update 335544451L -904 Object <string> is in use 335544453L -904 Cannot attach active shadow file 335544455L -904 A file in manual shadow <long> is unavailable 335544460L -904 Cannot add index, index root page is full. 335544661L -904 Sort error: not enough memory 335544676L -904 Request depth exceeded. (Recursive definition?) 335544683L -906 Product <string> is not licensed 335544452L -909 Drop database completed with errors 335544667L -911 Record from transaction <long> is stuck in limbo 335544459L -913 Deadlock 335544336L -922 File <string> is not a valid database 335544323L TABLE 6.4 SQLCODE codes and messages (continued) LANGUAGE REFERENCE 219
CHAPTER 6 ERROR CODES AND MESSAGES Firebird SQLCODE SQLCODE text number -923 Connection rejected by remote interface 335544421L -923 Secondary server attachments cannot validate databases 335544461L -923 Secondary server attachments cannot start journaling 335544462L -924 Bad parameters on attach or create database 335544325L -924 Database detach completed with errors 335544441L -924 Connection lost to pipe server 335544648L -926 No rollback performed 335544447L -999 Firebird error 335544689L TABLE 6.4 SQLCODE codes and messages (continued) Firebird status array error codes This section lists Firebird error codes and associated messages returned in the status array in the following tables. When code messages include the name of a database object or object type, the name is represented by a code in the Message column: g <string>: String value, such as the name of a database object or object type. g <digit>: Integer value, such as the identification number or code of a database object or object type. g <long>: Long integer value, such as the identification number or code of a database object or object type. 220
Firebird STATUS ARRAY ERROR CODES The following table lists SQL Status Array codes for embedded SQL programs, DSQL, and isql. Error code Number Message isc_arith_except 335544321L arithmetic exception, numeric overflow, or string truncation isc_bad_dbkey 335544322L invalid database key isc_bad_db_format 335544323L file <string> is not a valid database isc_bad_db_handle 335544324L invalid database handle (no active connection) isc_bad_dpb_content 335544325L bad parameters on attach or create database isc_bad_dpb_form 335544326L unrecognized database parameter block isc_bad_req_handle 335544327L invalid request handle isc_bad_segstr_handle 335544328L invalid Blob handle isc_bad_segstr_id 335544329L invalid Blob ID isc_bad_tpb_content 335544330L invalid parameter in transaction parameter block isc_bad_tpb_form 335544331L invalid format for transaction parameter block isc_bad_trans_handle 335544332L invalid transaction handle (expecting explicit transaction start) isc_bug_check 335544333L internal isc software consistency check (<string>) isc_convert_error 335544334L conversion error from string “<string>” isc_db_corrupt 335544335L database file appears corrupt (<string>) isc_deadlock 335544336L deadlock isc_excess_trans 335544337L attempt to start more than <long> transactions isc_from_no_match 335544338L no match for first value expression isc_infinap 335544339L information type inappropriate for object specified TABLE 6.5 Firebird status array error codes LANGUAGE REFERENCE 221
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_infona 335544340L no information of this type available for object specified isc_infunk 335544341L unknown information item isc_integ_fail 335544342L action cancelled by trigger (<long>) to preserve data integrity isc_invalid_blr 335544343L invalid request BLR at offset <long> isc_io_error 335544344L I/O error during “<string>” operation for file “<string>” isc_lock_conflict 335544345L lock conflict on no wait transaction isc_metadata_corrupt 335544346L corrupt system table isc_not_valid 335544347L validation error for column <string>, value “<string>” isc_no_cur_rec 335544348L no current record for fetch operation isc_no_dup 335544349L attempt to store duplicate value (visible to active transactions) in unique index “<string>” isc_no_finish 335544350L program attempted to exit without finishing database isc_no_meta_update 335544351L unsuccessful metadata update isc_no_priv 335544352L no permission for <string> access to <string> <string> isc_no_recon 335544353L transaction is not in limbo isc_no_record 335544354L invalid database key isc_no_segstr_close 335544355L Blob was not closed isc_obsolete_metadata 335544356L metadata is obsolete isc_open_trans 335544357L cannot disconnect database with open transactions (<long> active) TABLE 6.5 Firebird status array error codes (continued) 222
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_port_len 335544358L message length error (encountered <long>, expected <long>) isc_read_only_field 335544359L attempted update of read-only column isc_read_only_rel 335544360L attempted update of read-only table isc_read_only_trans 335544361L attempted update during read-only transaction isc_read_only_view 335544362L cannot update read-only view <string> isc_req_no_trans 335544363L no transaction for request isc_req_sync 335544364L request synchronization error isc_req_wrong_db 335544365L request referenced an unavailable database isc_segment 335544366L segment buffer length shorter than expected isc_segstr_eof 335544367L attempted retrieval of more segments than exist isc_segstr_no_op 335544368L attempted invalid operation on a Blob isc_segstr_no_read 335544369L attempted read of a new, open Blob isc_segstr_no_trans 335544370L attempted action on Blob outside transaction isc_segstr_no_write 335544371L attempted write to read-only Blob isc_segstr_wrong_db 335544372L attempted reference to Blob in unavailable database isc_sys_request 335544373L operating system directive <string> failed isc_stream_eof 335544374L attempt to fetch past the last record in a record stream isc_unavailable 335544375L unavailable database isc_unres_rel 335544376L Table <string> was omitted from the transaction reserving list isc_uns_ext 335544377L request includes a DSRI extension not supported in this implementation isc_wish_list 335544378L feature is not supported TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 223
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_wrong_ods 335544379L unsupported on-disk structure for file <string>; found <long>, support <long> isc_wronumarg 335544380L wrong number of arguments on call isc_imp_exc 335544381L Implementation limit exceeded isc_random 335544382L <string> isc_fatal_conflict 335544383L unrecoverable conflict with limbo transaction <long> isc_badblk 335544384L internal error isc_invpoolcl 335544385L internal error isc_nopoolids 335544386L too many requests isc_relbadblk 335544387L internal error isc_blktoobig 335544388L block size exceeds implementation restriction isc_bufexh 335544389L buffer exhausted isc_syntaxerr 335544390L BLR syntax error: expected <string> at offset <long>, encountered <long> isc_bufinuse 335544391L buffer in use isc_bdbincon 335544392L internal error isc_reqinuse 335544393L request in use isc_badodsver 335544394L incompatible version of on-disk structure isc_relnotdef 335544395L table <string> is not defined isc_fldnotdef 335544396L column <string> is not defined in table <string> isc_dirtypage 335544397L internal error isc_waifortra 335544398L internal error isc_doubleloc 335544399L internal error isc_nodnotfnd 335544400L internal error TABLE 6.5 Firebird status array error codes (continued) 224
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_dupnodfnd 335544401L internal error isc_locnotmar 335544402L internal error isc_badpagtyp 335544403L page <long> is of wrong type (expected <long>, found <long>) isc_corrupt 335544404L database corrupted isc_badpage 335544405L checksum error on database page <long> isc_badindex 335544406L index is broken isc_dbbnotzer 335544407L database handle not zero isc_tranotzer 335544408L transaction handle not zero isc_trareqmis 335544409L transaction—request mismatch (synchronization error) isc_badhndcnt 335544410L bad handle count isc_wrotpbver 335544411L wrong version of transaction parameter block isc_wroblrver 335544412L unsupported BLR version (expected <long>, encountered <long>) isc_wrodpbver 335544413L wrong version of database parameter block isc_blobnotsup 335544414L Blob and array datatypes are not supported for <string> operation isc_badrelation 335544415L database corrupted isc_nodetach 335544416L internal error isc_notremote 335544417L internal error isc_trainlim 335544418L transaction in limbo isc_notinlim 335544419L transaction not in limbo isc_traoutsta 335544420L transaction outstanding isc_connect_reject 335544421L connection rejected by remote interface TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 225
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_dbfile 335544422L internal error isc_orphan 335544423L internal error isc_no_lock_mgr 335544424L no lock manager available isc_ctxinuse 335544425L context already in use (BLR error) isc_ctxnotdef 335544426L context not defined (BLR error) isc_datnotsup 335544427L data operation not supported isc_badmsgnum 335544428L undefined message number isc_badparnum 335544429L bad parameter number isc_virmemexh 335544430L unable to allocate memory from operating system isc_blocking_signal 335544431L blocking signal has been received isc_lockmanerr 335544432L lock manager error isc_journerr 335544433L communication error with journal “<string>” isc_keytoobig 335544434L key size exceeds implementation restriction for index “<string>” isc_nullsegkey 335544435L null segment of UNIQUE KEY isc_sqlerr 335544436L SQL error code = <long> isc_wrodynver 335544437L wrong DYN version isc_funnotdef 335544438L function <string> is not defined isc_funmismat 335544439L function <string> could not be matched isc_bad_msg_vec 335544440L isc_bad_detach 335544441L database detach completed with errors isc_noargacc_read 335544442L database system cannot read argument <long> isc_noargacc_write 335544443L database system cannot write argument <long> TABLE 6.5 Firebird status array error codes (continued) 226
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_read_only 335544444L operation not supported isc_ext_err 335544445L <string> extension error isc_non_updatable 335544446L not updatable isc_no_rollback 335544447L no rollback performed isc_bad_sec_info 335544448L isc_invalid_sec_info 335544449L isc_misc_interpreted 335544450L <string> isc_update_conflict 335544451L update conflicts with concurrent update isc_unlicensed 335544452L product <string> is not licensed isc_obj_in_use 335544453L object <string> is in use isc_nofilter 335544454L filter not found to convert type <long> to type <long> isc_shadow_accessed 335544455L cannot attach active shadow file isc_invalid_sdl 335544456L invalid slice description language at offset <long> isc_out_of_bounds 335544457L subscript out of bounds isc_invalid_dimension 335544458L column not array or invalid dimensions (expected <long>, encountered <long>) isc_rec_in_limbo 335544459L record from transaction <long> is stuck in limbo isc_shadow_missing 335544460L a file in manual shadow <long> is unavailable isc_cant_validate 335544461L secondary server attachments cannot validate databases isc_cant_start_journal 335544462L secondary server attachments cannot start journaling isc_gennotdef 335544463L generator <string> is not defined TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 227
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_cant_start_logging 335544464L secondary server attachments cannot start logging isc_bad_segstr_type 335544465L invalid Blob type for operation isc_foreign_key 335544466L violation of FOREIGN KEY constraint: “<string>” isc_high_minor 335544467L minor version too high found <long> expected <long> isc_tra_state 335544468L transaction <long> is <string> isc_trans_invalid 335544469L transaction marked invalid by I/O error isc_buf_invalid 335544470L cache buffer for page <long> invalid isc_indexnotdefined 335544471L there is no index in table <string> with id <digit> isc_login 335544472L Your user name and password are not defined. Ask your database administrator to set up an Firebird login. isc_invalid_bookmark 335544473L invalid bookmark handle isc_bad_lock_level 335544474L invalid lock level <digit> isc_relation_lock 335544475L lock on table <string> conflicts with existing lock isc_record_lock 335544476L requested record lock conflicts with existing lock isc_max_idx 335544477L maximum indexes per table (<digit>) exceeded isc_jrn_enable 335544478L enable journal for database before starting online dump isc_old_failure 335544479L online dump failure. Retry dump isc_old_in_progress 335544480L an online dump is already in progress isc_old_no_space 335544481L no more disk/tape space. Cannot continue online dump isc_num_old_files 335544483L maximum number of online dump files that can be specified is 16 TABLE 6.5 Firebird status array error codes (continued) 228
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_bad_stmt_handle 335544485L invalid statement handle isc_stream_not_defined 335544502L reference to invalid stream number isc_shutinprog 335544506L database <string> shutdown in progress isc_range_in_use 335544507L refresh range number <long> already in use isc_range_not_found 335544508L refresh range number <long> not found isc_charset_not_found 335544509L character set <string> is not defined isc_lock_timeout 335544510L lock time-out on wait transaction isc_prcnotdef 335544511L procedure <string> is not defined isc_prcmismat 335544512L parameter mismatch for procedure <string> isc_codnotdef 335544515L status code <string> unknown isc_xcpnotdef 335544516L exception <string> not defined isc_except 335544517L exception <digit> isc_cache_restart 335544518L restart shared cache manager isc_bad_lock_handle 335544519L invalid lock handle isc_shutdown 335544528L database <string> shutdown isc_existing_priv_mod 335544529L cannot modify an existing user privilege isc_primary_key_ref 335544530L Cannot delete PRIMARY KEY being used in FOREIGN KEY definition. isc_primary_key_notnull 335544531L Column used in a PRIMARY/UNIQUE constraint must be NOT NULL. isc_ref_cnstrnt_notfound 335544532L Name of Referential Constraint not defined in constraints table. isc_foreign_key_notfound 335544533L Non-existent PRIMARY or UNIQUE KEY specified for FOREIGN KEY. isc_ref_cnstrnt_update 335544534L Cannot update constraints (RDB$REF_CONSTRAINTS). TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 229
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_check_cnstrnt_update 335544535L Cannot update constraints (RDB$CHECK_CONSTRAINTS). isc_check_cnstrnt_del 335544536L Cannot delete CHECK constraint entry (RDB$CHECK_CONSTRAINTS) isc_integ_index_seg_del 335544537L Cannot delete index segment used by an Integrity Constraint isc_integ_index_seg_mod 335544538L Cannot update index segment used by an Integrity Constraint isc_integ_index_del 335544539L Cannot delete index used by an Integrity Constraint isc_integ_index_mod 335544540L Cannot modify index used by an Integrity Constraint isc_check_trig_del 335544541L Cannot delete trigger used by a CHECK Constraint isc_check_trig_update 335544542L Cannot update trigger used by a CHECK Constraint isc_cnstrnt_fld_del 335544543L Cannot delete column being used in an Integrity Constraint. isc_cnstrnt_fld_rename 335544544L Cannot rename column being used in an Integrity Constraint. isc_rel_cnstrnt_update 335544545L Cannot update constraints (RDB$RELATION_CONSTRAINTS). isc_constaint_on_view 335544546L Cannot define constraints on views isc_invld_cnstrnt_type 335544547L internal isc software consistency check (invalid RDB$CONSTRAINT_TYPE) isc_primary_key_exists 335544548L Attempt to define a second PRIMARY KEY for the same table isc_systrig_update 335544549L cannot modify or erase a system trigger isc_not_rel_owner 335544550L only the owner of a table may reassign ownership isc_grant_obj_notfound 335544551L could not find table/procedure for GRANT TABLE 6.5 Firebird status array error codes (continued) 230
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_grant_fld_notfound 335544552L could not find column for GRANT isc_grant_nopriv 335544553L user does not have GRANT privileges for operation isc_nonsql_security_rel 335544554L table/procedure has non-SQL security class defined isc_nonsql_security_fld 335544555L column has non-SQL security class defined isc_shutfail 335544557L database shutdown unsuccessful isc_check_constraint 335544558L Operation violates CHECK constraint <string> on view or table isc_bad_svc_handle 335544559L invalid service handle isc_shutwarn 335544560L database <string> shutdown in <digit> seconds isc_wrospbver 335544561L wrong version of service parameter block isc_bad_spb_form 335544562L unrecognized service parameter block isc_svcnotdef 335544563L service <string> is not defined isc_no_jrn 335544564L long-term journaling not enabled isc_transliteration_failed 335544565L Cannot transliterate character between character sets isc_text_subtype 335544568L Implementation of text subtype <digit> not located. isc_dsql_error 335544569L Dynamic SQL Error isc_dsql_command_err 335544570L Invalid command isc_dsql_constant_err 335544571L Datatype for constant unknown isc_dsql_cursor_err 335544572L Cursor unknown isc_dsql_datatype_err 335544573L Datatype unknown isc_dsql_decl_err 335544574L Declared cursor already exists isc_dsql_cursor_update_err 335544575L Cursor not updatable TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 231
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_dsql_cursor_open_err 335544576L Attempt to reopen an open cursor isc_dsql_cursor_close_err 335544577L Attempt to reclose a closed cursor isc_dsql_field_err 335544578L Column unknown isc_dsql_internal_err 335544579L Internal error isc_dsql_relation_err 335544580L Table unknown isc_dsql_procedure_err 335544581L Procedure unknown isc_dsql_request_err 335544582L Request unknown isc_dsql_sqlda_err 335544583L SQLDA missing or incorrect version, or incorrect number/type of variables isc_dsql_var_count_err 335544584L Count of columns not equal count of values isc_dsql_stmt_handle 335544585L Invalid statement handle isc_dsql_function_err 335544586L Function unknown isc_dsql_blob_err 335544587L Column is not a Blob isc_collation_not_found 335544588L COLLATION <string> is not defined isc_collation_not_for_charset 335544589L COLLATION <string> is not valid for specified CHARACTER SET isc_dsql_dup_option 335544590L Option specified more than once isc_dsql_tran_err 335544591L Unknown transaction option isc_dsql_invalid_array 335544592L Invalid array reference isc_dsql_max_arr_dim_exceeded 335544593L Array declared with too many dimensions isc_dsql_arr_range_error 335544594L Illegal array dimension range isc_dsql_trigger_err 335544595L Trigger unknown isc_dsql_subselect_err 335544596L Subselect illegal in this context isc_dsql_crdb_prepare_err 335544597L Cannot prepare a CREATE DATABASE/SCHEMA statement TABLE 6.5 Firebird status array error codes (continued) 232
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_specify_field_err 335544598L must specify column name for view select expression isc_num_field_err 335544599L number of columns does not match select list isc_col_name_err 335544600L Only simple column names permitted for VIEW WITH CHECK OPTION isc_where_err 335544601L No WHERE clause for VIEW WITH CHECK OPTION isc_table_view_err 335544602L Only one table allowed for VIEW WITH CHECK OPTION isc_distinct_err 335544603L DISTINCT, GROUP or HAVING not permitted for VIEW WITH CHECK OPTION isc_key_field_count_err 335544604L FOREIGN KEY column count does not match PRIMARY KEY isc_subquery_err 335544605L No subqueries permitted for VIEW WITH CHECK OPTION isc_expression_eval_err 335544606L expression evaluation not supported isc_node_err 335544607L gen.c: node not supported isc_command_end_err 335544608L Unexpected end of command isc_index_name 335544609L INDEX <string> isc_exception_name 335544610L EXCEPTION <string> isc_field_name 335544611L COLUMN <string> isc_token_err 335544612L Token unknown isc_union_err 335544613L union not supported isc_dsql_construct_err 335544614L Unsupported DSQL construct isc_field_aggregate_err 335544615L column used with aggregate isc_field_ref_err 335544616L invalid column reference isc_order_by_err 335544617L invalid ORDER BY clause TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 233
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_return_mode_err 335544618L Return mode by value not allowed for this datatype isc_extern_func_err 335544619L External functions cannot have more than 10 parameters isc_alias_conflict_err 335544620L alias <string> conflicts with an alias in the same statement isc_procedure_conflict_error 335544621L alias <string> conflicts with a procedure in the same statement isc_relation_conflict_err 335544622L alias <string> conflicts with a table in the same statement isc_dsql_domain_err 335544623L Illegal use of keyword VALUE isc_idx_seg_err 335544624L segment count of 0 defined for index <string> isc_node_name_err 335544625L A node name is not permitted in a secondary, shadow, cache or log file name isc_table_name 335544626L TABLE <string> isc_proc_name 335544627L PROCEDURE <string> isc_idx_create_err 335544628L cannot create index <string> isc_dependency 335544630L there are <long> dependencies isc_idx_key_err 335544631L too many keys defined for index <string> isc_dsql_file_length_err 335544632L Preceding file did not specify length, so <string> must include starting page number isc_dsql_shadow_number_err 335544633L Shadow number must be a positive integer isc_dsql_token_unk_err 335544634L Token unknown - line <long>, char <long> isc_dsql_no_relation_alias 335544635L there is no alias or table named <string> at this scope level isc_indexname 335544636L there is no index <string> for table <string> isc_no_stream_plan 335544637L table <string> is not referenced in plan TABLE 6.5 Firebird status array error codes (continued) 234
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_stream_twice 335544638L table <string> is referenced more than once in plan; use aliases to distinguish isc_stream_not_found 335544639L table <string> is referenced in the plan but not the from list isc_collation_requires_text 335544640L Invalid use of CHARACTER SET or COLLATE isc_dsql_domain_not_found 335544641L Specified domain or source column does not exist isc_index_unused 335544642L index <string> cannot be used in the specified plan isc_dsql_self_join 335544643L the table <string> is referenced twice; use aliases to differentiate isc_stream_bof 335544644L illegal operation when at beginning of stream isc_stream_crack 335544645L the current position is on a crack isc_db_or_file_exists 335544646L database or file exists isc_invalid_operator 335544647L invalid comparison operator for find operation isc_conn_lost 335544648L Connection lost to pipe server isc_bad_checksum 335544649L bad checksum isc_page_type_err 335544650L wrong page type isc_ext_readonly_err 335544651L external file could not be opened for output isc_sing_select_err 335544652L multiple rows in singleton select isc_psw_attach 335544653L cannot attach to password database isc_psw_start_trans 335544654L cannot start transaction for password database isc_invalid_direction 335544655L invalid direction for find operation isc_dsql_var_conflict 335544656L variable <string> conflicts with parameter in same procedure isc_dsql_no_blob_array 335544657L Array/Blob/DATE /TIME/TIMESTAMP datatypes not allowed in arithmetic TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 235
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_dsql_base_table 335544658L <string> is not a valid base table of the specified view isc_duplicate_base_table 335544659L table <string> is referenced twice in view; use an alias to distinguish isc_view_alias 335544660L view <string> has more than one base table; use aliases to distinguish isc_index_root_page_full 335544661L cannot add index, index root page is full. isc_dsql_blob_type_unknown 335544662L BLOB SUB_TYPE <string> is not defined isc_req_max_clones_exceeded 335544663L Too many concurrent executions of the same request isc_dsql_duplicate_spec 335544664L duplicate specification of <string> - not supported isc_unique_key_violation 335544665L violation of PRIMARY or UNIQUE KEY constraint: “<string>” isc_srvr_version_too_old 335544666L server version too old to support all CREATE DATABASE options isc_drdb_completed_with_errs 335544667L drop database completed with errors isc_dsql_procedure_use_err 335544668L procedure <string> does not return any values isc_dsql_count_mismatch 335544669L count of column list and variable list do not match isc_blob_idx_err 335544670L attempt to index Blob column in index <string> isc_array_idx_err 335544671L attempt to index array column in index <string> isc_key_field_err 335544672L too few key columns found for index <string> (incorrect column name?) isc_no_delete 335544673L cannot delete isc_del_last_field 335544674L last column in a table cannot be deleted isc_sort_err 335544675L sort error TABLE 6.5 Firebird status array error codes (continued) 236
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_sort_mem_err 335544676L sort error: not enough memory isc_version_err 335544677L too many versions isc_inval_key_posn 335544678L invalid key position isc_no_segments_err 335544679L segments not allowed in expression index <string> isc_crrp_data_err 335544680L sort error: corruption in data structure isc_rec_size_err 335544681L new record size of <long> bytes is too big isc_dsql_field_ref 335544682L Inappropriate self-reference of column isc_req_depth_exceeded 335544683L request depth exceeded. (Recursive definition?) isc_no_field_access 335544684L cannot access column <string> in view <string> isc_no_dbkey 335544685L dbkey not available for multi-table views isc_dsql_open_cursor_request 335544688L The prepare statement identifies a prepare statement with an open cursor isc_ib_error 335544689L Firebird error isc_cache_redef 335544690L Cache redefined isc_cache_too_small 335544691L Cache length too small isc_precision_err 335544697L Precision should be greater than 0 isc_scale_nogt 335544698L Scale cannot be greater than precision isc_expec_short 335544699L Short integer expected isc_expec_long 335544700L Long integer expected isc_expec_ushort 335544701L Unsigned short integer expected isc_like_escape_invalid 335544702L Invalid ESCAPE sequence isc_svcnoexe 335544703L service <string> does not have an associated executable isc_net_lookup_err 335544704L Network lookup failure for host “<string>” TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 237
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_service_unknown 335544705L Undefined service <string>/<string> isc_host_unknown 335544706L Host unknown isc_grant_nopriv_on_base 335544707L user does not have GRANT privileges on base table/view for operation isc_dyn_fld_ambiguous 335544708L Ambiguous column reference. isc_dsql_agg_ref_err 335544709L Invalid aggregate reference isc_complex_view 335544710L navigational stream <long> references a view with more than one base table. isc_unprepared_stmt 335544711L attempt to execute an unprepared dynamic SQL statement isc_expec_positive 335544712L Positive value expected. isc_dsql_sqlda_value_err 335544713L Incorrect values within SQLDA structure isc_invalid_array_id 335544714L invalid Blob id isc_ext_file_uns_op 335544715L operation not supported for EXTERNAL FILE table <string> isc_svc_in_use 335544716L service is currently busy: <string> isc_err_stack_limit 335544717L stack size insufficient to execute current request isc_invalid_key 335544718L invalid key for find operation isc_net_init_error 335544719L error initializing the network software isc_loadlib_failure 335544720L unable to load required library <string> isc_network_error 335544721L unable to complete network request to host “<string>” isc_net_connect_err 335544722L failed to establish a connection isc_net_connect_listen_err 335544723L error while listening for an incoming connection isc_net_event_connect_err 335544724L failed to establish a secondary connection for event processing TABLE 6.5 Firebird status array error codes (continued) 238
Firebird STATUS ARRAY ERROR CODES Error code Number Message isc_net_event_listen_err 335544725L error while listening for an incoming event connection request isc_net_read_err 335544726L error reading data from the connection isc_net_write_err 335544727L error writing data to the connection isc_integ_index_deactivate 335544728L cannot deactivate index used by an Integrity Constraint isc_integ_deactivate_primary 335544729L cannot deactivate primary index isc_unsupported_network_drive 335544732L access to databases on file servers is not supported isc_io_create_err 335544733L error while trying to create file isc_io_open_err 335544734L error while trying to open file isc_io_close_err 335544735L error while trying to close file isc_io_read_err 335544736L error while trying to read from file isc_io_write_err 335544737L error while trying to write to file isc_io_delete_err 335544738L error while trying to delete file isc_io_access_err 335544739L error while trying to access file isc_udf_exception 335544740L exception <integer> detected in blob filter or user defined function isc_lost_db_connection 335544741L connection lost to database isc_no_write_user_priv 335544742L user cannot write to RDB$USER_PRIVILEGES isc_token_too_long 335544743L token size exceeds limit isc_max_att_exceeded 335544744L maximum user count exceeded; contact your database administrator isc_login_same_as_role_name 335544745L your login <string> is same as one of the SQL role names; ask your database administrator to set up a valid Firebird login TABLE 6.5 Firebird status array error codes (continued) LANGUAGE REFERENCE 239
CHAPTER 6 ERROR CODES AND MESSAGES Error code Number Message isc_reftable_requires_pk 335544746L “REFERENCES table” without “(column)”; requires PRIMARY KEY on referenced table isc_usrname_too_long 335544747L the username entered is too long. Maximum length is 31 bytes. isc_password_too_long 335544748L the password specified is too long. Maximum length is 8 bytes. isc_usrname_required 335544749L a username is required for this operation. isc_password_required 335544750L a password is required for this operation isc_bad_protocol 335544751L the network protocol specified is invalid isc_dup_usrname_found 335544752L a duplicate user name was found in the security database isc_usrname_not_found 335544753L the user name specified was not found in the security database isc_error_adding_sec_record 335544754L error while attempting to add the user isc_error_modifying_sec_record 335544755L error while attempting to modify the user record isc_error_deleting_sec_record 335544756L error while attempting to delete the user record eisc_rror_updating_sec_db 335544757L error while updating the security database isc_sort_rec_size_err 335544758L sort record size is too big isc_bad_default_value 335544759L cannot assign a NULL default value to a column with a NOT NULL constraint isc_invalid_clause 335544760L the specified user-entered string is not valid isc_too_many_handles 335544761L too many open handles to database isc_optimizer_blk_exc 335544762L optimizer implementation limits are exceeded; for example, only 256 conjuncts (ANDs and ORs) are allowed TABLE 6.5 Firebird status array error codes (continued) 240
CHAPTER 7 System Tables and Views Chapter 7 This chapter describes the Firebird system tables and SQL system views. IMPORTANT Only Firebird system object names can begin with the characters “RDB$”. No other object name in Firebird can begin with this character sequence, including tables, views, triggers, stored procedures, indexes, generators, domains, and roles. Overview The Firebird system tables contain and track metadata. Firebird automatically creates system tables when a database is created. Each time a user creates or modifies metadata through data definition, the SQL data definition utility automatically updates the system tables. SQL system views provide information about existing integrity constraints for a database. You must create system views yourself by creating and running an isql script after database definition. See “System views” on page 273 for the code that creates them as well as the resulting table structures. To see system tables, use this isql command: SHOW SYSTEM TABLES; The following isql command lists system views along with database views: LANGUAGE REFERENCE 241
CHAPTER 7 SYSTEM TABLES AND VIEWS SHOW VIEWS; System tables This table lists the Firebird system tables. The names of system tables and their columns start with RDB$. RDB$CHARACTER_SETS RDB$LOG_FILES RDB$COLLATIONS RDB$PAGES RDB$CHECK_CONSTRAINTS RDB$PROCEDURE_PARAMETERS RDB$DATABASE RDB$PROCEDURES RDB$DEPENDENCIES RDB$REF_CONSTRAINTS RDB$EXCEPTIONS RDB$RELATION_CONSTRAINTS RDB$FIELD_DIMENSIONS RDB$RELATION_FIELDS RDB$FIELDS RDB$RELATIONS RDB$FILES RDB$ROLES RDB$FILTERS RDB$SECURITY_CLASSES RDB$FORMATS RDB$TRANSACTIONS RDB$FUNCTION_ARGUMENTS RDB$TRIGGER_MESSAGES RDB$FUNCTIONS RDB$TRIGGERS RDB$GENERATORS RDB$TYPES RDB$INDEX_SEGMENTS RDB$USER_PRIVILEGES RDB$INDICES RDB$VIEW_RELATIONS TABLE 7.1 System tables 242
RDB$CHARACTER_SETS RDB$CHARACTER_SETS RDB$CHARACTER_SETS describes the valid character sets available in Firebird. Column name Datatype Length Description RDB$CHARACTER_SET_NAME CHAR 31 Name of a character set that Firebird recognizes RDB$FORM_OF_USE CHAR 31 Reserved for internal use. Subtype 2 RDB$NUMBER_OF_CHARACTERS INTEGER Number of characters in a particular character set; for example, the set of Japanese characters RDB$DEFAULT_COLLATE_NAME CHAR 31 Subtype 2: default collation sequence for the character set RDB$CHARACTER_SET_ID SMALLINT A unique identification for the character set RDB$SYSTEM_FLAG SMALLINT Indicates whether the character set is: • User-defined (value of 0 or NULL)• System-defined (value of 1) RDB$DESCRIPTION BLOB 80 Subtype text: Contains a user-written description of the character set RDB$FUNCTION_NAME CHAR 31 Reserved for internal use; subtype 2 RDB$BYTES_PER_CHARACTER SMALLINT Size of character in bytes TABLE 7.2 RDB$CHARACTER_SETS LANGUAGE REFERENCE 243
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$CHECK_CONSTRAINTS RDB$CHECK_CONSTRAINTS stores database integrity constraint information for CHECK constraints. In addition, the table stores information for constraints implemented with NOT NULL. Column name Datatype Length Description RDB$CONSTRAINT_NAME CHAR 31 Subtype 2: Name of a CHECK or NOT NULL constraint RDB$TRIGGER_NAME CHAR 31 Subtype 2: Name of the trigger that enforces the CHECK constraint; for a NOT NULL constraint, name of the source column in RDB$RELATION_FIELDS TABLE 7.3 RDB$CHECK_CONSTRAINTS RDB$COLLATIONS RDB$COLLATIONS records the valid collating sequences available for use in Firebird. Column name Datatype Length Description RDB$COLLATION_NAME CHAR 31 Name of a valid collation sequence in Firebird RDB$COLLATION_ID SMALLINT Unique identifier for the collation sequence RDB$CHARACTER_SET_ID SMALLINT Identifier of the underlying character set of this collation sequence • Required before collation can proceed• Determines which character set is in use Corresponds to the RDB$CHARACTER_SET_ID column in the RDB$CHARACTER_SETS table RDB$COLLATION_ATTRIBUTES SMALLINT Reserved for internal use TABLE 7.4 RDB$COLLATIONS 244
RDB$DATABASE Column name Datatype Length Description RDB$SYSTEM_FLAG SMALLINT Indicates whether the generator is: • User-defined (value of 0)• System-defined (value greater than 0) RDB$DESCRIPTION BLOB 80 Subtype Text: Contains a user-written description of the collation sequence RDB$FUNCTION_NAME CHAR 31 Reserved for internal use TABLE 7.4 RDB$COLLATIONS (continued) RDB$DATABASE RDB$DATABASE defines a database. Column name Datatype Length Description RDB$DESCRIPTION BLOB 80 Subtype Text: Contains a user-written description of the database; when a comment is included in a CREATE or ALTER SCHEMA|DATABASE statement, isql writes to this column RDB$RELATION_ID SMALLINT For internal use by Firebird RDB$SECURITY_CLASS CHAR 31 Subtype 2: Security class defined in the RDB$SECURITY_CLASSES table; the access control limits described in the named security class apply to all database usage RDB$CHARACTER_SET_NAME CHAR 31 Subtype 2; Name of character set TABLE 7.5 RDB$DATABASE LANGUAGE REFERENCE 245
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$DEPENDENCIES RDB$DEPENDENCIES keeps track of the tables and columns upon which other system objects depend. These objects include views, triggers, and computed columns. Firebird uses this table to ensure that a column or table cannot be deleted if it is used by any other object. Column name Datatype Length Description RDB$DEPENDENT_NAME CHAR 31 Subtype 2; names the object this table tracks: a view, trigger, or computed column RDB$DEPENDED_ON_NAME CHAR 31 Subtype 2; names the table referenced by the object named above RDB$FIELD_NAME CHAR 31 Subtype 2; names the column referenced by the object named above RDB$DEPENDENT_TYPE SMALLINT Describes the object type of the object referenced in the RDB$DEPENDENT_NAME column; type codes (RDB$TYPES): • 0 - table • 6 - expression_index • 1 - view • 7 - exception • 2 - trigger • 8 - user • 3 - computed_field • 9 - field • 4 - validation • 10 - index • 5 - procedure All other values are reserved for future use TABLE 7.6 RDB$DEPENDENCIES 246
RDB$EXCEPTIONS Column name Datatype Length Description RDB$DEPENDED_ON_TYPE SMALLINT Describes the object type of the object referenced in the RDB$DEPENDED_ON_NAME column; type codes (RDB$TYPES): • 0 - table • 6 - expression_index • 1 - view • 7 - exception • 2 - trigger • 8 - user • 3 - computed_field • 9 - field • 4 - validation • 10 - index • 5 - procedure All other values are reserved for future use TABLE 7.6 RDB$DEPENDENCIES RDB$EXCEPTIONS RDB$EXCEPTIONS describes error conditions related to stored procedures, including user-defined exceptions. Column name Datatype Length Description RDB$EXCEPTION_NAME CHAR 31 Subtype 2; exception name RDB$EXCEPTION_NUMBER INTEGER Number for the exception RDB$MESSAGE VARCHAR 78 Text of exception message RDB$DESCRIPTION BLOB 80 Subtype Text: Text description of the exception RDB$SYSTEM_FLAG SMALLINT Indicates whether the exception is: • User-defined (value of 0)• System-defined (value greater than 0) TABLE 7.7 RDB$EXCEPTIONS LANGUAGE REFERENCE 247
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$FIELD_DIMENSIONS RDB$FIELD_DIMENSIONS describes each dimension of an array column. Column name Datatype Length Description RDB$FIELD_NAME CHAR 31 Subtype 2; names the array column described by this table; the column name must exist in the RDB$FIELD_NAME column of RDB$FIELDS RDB$DIMENSION SMALLINT Identifies one dimension of the ARRAY column; the first dimension is identified by the integer 0 RDB$LOWER_BOUND INTEGER Indicates the lower bound of the previously specified dimension RDB$UPPER_BOUND INTEGER Indicates the upper bound of the previously specified dimension TABLE 7.8 RDB$FIELD_DIMENSIONS RDB$FIELDS RDB$FIELDS defines the characteristics of a column. Each domain or column has a corresponding row in RDB$FIELDS. Columns are added to tables by means of an entry in the RDB$RELATION_FIELDS table, which describes local characteristics. For domains, RDB$FIELDS includes domain name, null status, and default values. SQL columns are defined in RDB$RELATION_FIELDS. For both domains and simple columns, RDB_RELATION_FIELDS can contain default and null status information. Column name Datatype Length Description RDB$FIELD_NAME CHAR 31 Unique name of a domain or system-assigned name for a column, starting with SQLnnn; the actual column names are stored in the RDB$FIELD_SOURCE column of RDB$RELATION_FIELDS RDB$QUERY_NAME CHAR 31 Not used for SQL objects RDB$VALIDATION_BLR BLOB 80 Not used for SQL objects RDB$VALIDATION_SOURCE BLOB 80 Not used for SQL objects TABLE 7.9 RDB$FIELDS 248
RDB$FIELDS Column name Datatype Length Description RDB$COMPUTED_BLR BLOB 80 Subtype BLR; for computed columns, contains the BLR (Binary Language Representation) of the expression the database evaluates at the time of execution RDB$COMPUTED_SOURCE BLOB 80 Subtype Text: For computed columns, contains the original CHAR source expression for the column RDB$DEFAULT_VALUE BLOB 80 Stores default rule; subtype BLR RDB$DEFAULT_SOURCE BLOB 80 Subtype Text; SQL description of a default value RDB$FIELD_LENGTH SMALLINT Contains the length of the column defined in this row; non-CHAR column lengths are: • D_FLOAT - 8 • SHORT - 2 • DOUBLE - 8 • LONG - 4 • DATE - 4 • QUAD - 8 • BLOB - 8 • FLOAT - 4 • TIME - 4 • TIMESTAMP - 8 • INT64 - 8 RDB$FIELD_PRECISION SMALLINT Stores the precision for numeric and decimal types RDB$FIELD_SCALE SMALLINT Stores negative scale for numeric and decimal types TABLE 7.9 RDB$FIELDS (continued) LANGUAGE REFERENCE 249
CHAPTER 7 SYSTEM TABLES AND VIEWS Column name Datatype Length Description RDB$FIELD_TYPE SMALLINT Specifies the datatype of the column being defined; changing the value of this column automatically changes the datatype for all columns based on the column being defined Valid values are: • BLOB - 261 • QUAD - 9 • CHAR - 14 • SMALLINT - 7 • CSTRING - 40 • DATE - 12 • D_FLOAT - 11 (dialect 3 DATE) • DOUBLE - 27 • TIME - 13 • FLOAT - 10 • TIMESTAMP - 35 • ( INT64 - 16 DATE in older versions) • • VARCHAR - 37 INTEGER - 8 Restrictions: • The value of this column cannot be changed to or from Blob • Non-numeric data causes a conversion error in a column changed from CHAR to numeric Changing data from CHAR to numeric and back again adversely affects index performance; for best results, delete and re-create indexes when making this type of change TABLE 7.9 RDB$FIELDS (continued) 250
RDB$FIELDS Column name Datatype Length Description RDB$FIELD_SUB_TYPE SMALLINT Used to distinguish types of Blobs, CHARs, and integers 1 If RDB$FIELD_TYPE is 261 (Blob), predefined subtypes can be: • 0 - unspecified • 5 - encoded description • 1 - text of a table’s current • 2 - BLR (Binary Language metadata Representation) • 6 - description of • 3 - access control list multi-database transaction that finished • 4 - reserved for future use irregularly 2 If RDB$FIELD_TYPE is 14 (CHAR ), columns can be: • 0 - type is unspecified• 1 - fixed BINARY dataCorresponds to the RDB$FIELD_SUB_TYPE column in the RDB$COLLATIONS table 3 If RDB$FIELD_TYPE is 7 (SMALLINT), 8 (INTEGER), or 16 (INT64), the original declaration was: • 0 or NULL - RDB$FIELD_TYPE• 1 - NUMERIC• 2 - DECIMAL RDB$MISSING_VALUE BLOB 80 Not used for SQL objects RDB$MISSING_SOURCE BLOB 80 Not used for SQL objects RDB$DESCRIPTION BLOB 80 Subtype Text: Contains a user-written description of the column being defined RDB$SYSTEM_FLAG SMALLINT For system tables RDB$QUERY_HEADER BLOB 80 Not used for SQL objects RDB$SEGMENT_LENGTH SMALLINT Used for Blob columns only; a non-binding suggestion for the length of Blob buffers RDB$EDIT_STRING VARCHAR 125 Not used for SQL objects RDB$EXTERNAL_LENGTH SMALLINT Length of the column as it exists in an external table; if the column is not in an external table, this value is 0 TABLE 7.9 RDB$FIELDS (continued) LANGUAGE REFERENCE 251
CHAPTER 7 SYSTEM TABLES AND VIEWS Column name Datatype Length Description RDB$EXTERNAL_SCALE SMALLINT Scale factor for an external column of an integer datatype; the scale factor is the power of 10 by which the integer is multiplied RDB$EXTERNAL_TYPE SMALLINT Indicates the datatype of the column as it exists in an external table; valid values are: • SMALLINT - 7 • DOUBLE - 27 • INTEGER - 8 • DATE - 35 • QUAD - 9 • VARCHAR - 37 • FLOAT - 10 • ‘C’ string (null • D_FLOAT - 11 terminated text) - 40 • CHAR - 14 • BLOB - 261 • TIME • TIMESTAMP RDB$DIMENSIONS SMALLINT For an ARRAY datatype, specifies the number of dimensions in the array; for a non-array column, the value is 0 RDB$NULL_FLAG SMALLINT Indicates whether a column can contain a NULL value Valid values are: • Empty: Can contain NULL values• 1: Cannot contain NULL values RDB$CHARACTER_LENGTH SMALLINT Length of character in bytes RDB$COLLATION_ID SMALLINT Unique identifier for the collation sequence RDB$CHARACTER_SET_ID SMALLINT ID indicating character set for the character or Blob columns; joins to the CHARACTER_SET_ID column of the RDB$CHARACTER_SETS system table TABLE 7.9 RDB$FIELDS (continued) 252
RDB$FILES RDB$FILES RDB$FILES lists the secondary files and shadow files for a database. Column name Datatype Length Description RDB$FILE_NAME VARCHAR 253 Names either a secondary file or a shadow file for the database RDB$FILE_SEQUENCE SMALLINT Either the order that secondary files are to be used in the database or the order of files within a shadow set RDB$FILE_START INTEGER Specifies the starting page number for a secondary file or shadow file RDB$FILE_LENGTH INTEGER Specifies the file length in blocks RDB$FILE_FLAGS SMALLINT Reserved for system use RDB$SHADOW_NUMBER SMALLINT Set number: indicates to which shadow set the file belongs; if the value of this column is 0 or missing, Firebird assumes the file being defined is a secondary file, not a shadow file TABLE 7.10 RDB$FILES LANGUAGE REFERENCE 253
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$FILTERS RDB$FILTERS tracks information about a Blob filter. Column name Datatype Length Description RDB$FUNCTION_NAME CHAR 31 Unique name for the filter defined by this row RDB$DESCRIPTION BLOB 80 Subtype Text: Contains a user-written description of the filter being defined RDB$MODULE_NAME VARCHAR 253 Names the library where the filter executable is stored RDB$ENTRYPOINT CHAR 31 The entry point within the filter library for the Blob filter being defined RDB$INPUT_SUB_TYPE SMALLINT The Blob subtype of the input data RDB$OUTPUT_SUB_TYPE SMALLINT The Blob subtype of the output data RDB$SYSTEM_FLAG SMALLINT Indicates whether the filter is: • User-defined (value of 0)• System-defined (value greater than 0) TABLE 7.11 RDB$FILTERS RDB$FORMATS RDB$FORMATS keeps track of the formats of the columns in a table. Firebird assigns the table a new format number at each change to a column definition. This table allows existing application programs to access a changed table, without needing to be recompiled. Column name Datatype Length Description RDB$RELATION_ID SMALLINT Names a table that exists in RDB$RELATIONS RDB$FORMAT SMALLINT Specifies the format number of the table; a table can have any number of different formats, depending on the number of updates to the table RDB$DESCRIPTOR BLOB 80 Subtype Format: Lists each column in the table, along with its datatype, length, and scale (if applicable) TABLE 7.12 RDB$FORMATS 254
RDB$FUNCTION_ARGUMENTS RDB$FUNCTION_ARGUMENTS RDB$FUNCTION_ARGUMENTS defines the attributes of a function argument. Column name Datatype Length Description RDB$FUNCTION_NAME CHAR 31 Unique name of the function with which the argument is associated; must correspond to a function name in RDB$FUNCTIONS RDB$ARGUMENT_POSITION SMALLINT Position of the argument described in the RDB$FUNCTION_NAME column in relation to the other arguments RDB$MECHANISM SMALLINT Specifies whether the argument is passed by value (value of 0) or by reference (value of 1) RDB$FIELD_TYPE SMALLINT Datatype of the argument being defined Valid values are: • BLOB - 261 • QUAD - 9 • CHAR - 14 • SMALLINT - 7 • CSTRING - 40 • DATE - 12 • D_FLOAT - 11 (dialect 3 DATE) • DOUBLE - 27 • TIME - 13 • FLOAT - 10 • TIMESTAMP - 35 • (DATE in older versions) INT64 - 16 • • INTEGER - 8 VARCHAR - 37 RDB$FIELD_SCALE SMALLINT Scale factor for an argument that has an integer datatype; the scale factor is the power of 10 by which the integer is multiplied TABLE 7.13 RDB$FUNCTION_ARGUMENTS LANGUAGE REFERENCE 255
CHAPTER 7 SYSTEM TABLES AND VIEWS Column name Datatype Length Description RDB$FIELD_LENGTH SMALLINT The length of the argument defined in this row Valid column lengths are: • BLOB - 8 • INTEGER - 4 • D_FLOAT - 8 • QUAD - 8 • DATE - 4 • SMALLINT - 2 • DOUBLE - 8 • TIME - 4 • FLOAT - 4 • TIMESTAMP - 8 • INT64 - 8 RDB$FIELD_SUB_TYPE SMALLINT How SMALLINT, INTEGER, and INT64 columns were declared: • 0 or NULL - RDB$FIELD_TYPE• 1 - NUMERIC• 2 - DECIMAL RDB$CHARACTER_SET_ID SMALLINT Unique numeric identifier for a character set RDB$FIELD_PRECISION SMALLINT The declared precision of the DECIMAL or NUMERIC function argument TABLE 7.13 RDB$FUNCTION_ARGUMENTS (continued) RDB$FUNCTIONS RDB$FUNCTIONS defines a user-defined function. Column name Datatype Length Description RDB$FUNCTION_NAME CHAR 31 Unique name for a function RDB$FUNCTION_TYPE SMALLINT Reserved for future use RDB$QUERY_NAME CHAR 31 Alternate name for the function that can be used in isql RDB$DESCRIPTION BLOB 80 Subtype Text: Contains a user-written description of the function being defined TABLE 7.14 RDB$FUNCTIONS 256
RDB$GENERATORS Column name Datatype Length Description RDB$MODULE_NAME VARCHAR 253 Names the function library where the executable function is stored RDB$ENTRYPOINT CHAR 31 Entry point within the function library for the function being defined RDB$RETURN_ARGUMENT SMALLINT Position of the argument returned to the calling program; this position is specified in relation to other arguments RDB$SYSTEM_FLAG SMALLINT Indicates whether the function is: • User-defined (value of 0)• System-defined (value of 1) TABLE 7.14 RDB$FUNCTIONS (continued) RDB$GENERATORS RDB$GENERATORS stores information about generators, which provide the ability to generate a unique identifier for a table. Column name Datatype Length Description RDB$GENERATOR_NAME CHAR 31 Name of the table to contain the unique identifier produced by the number generator RDB$GENERATOR_ID SMALLINT Unique system-assigned ID number for the generator RDB$SYSTEM_FLAG SMALLINT Indicates whether the generator is: • User-defined (value of 0)• System-defined (value greater than 0) TABLE 7.15 RDB$GENERATORS LANGUAGE REFERENCE 257
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$INDEX_SEGMENTS RDB$INDEX_SEGMENTS specifies the columns that comprise an index for a table. Modifying these rows corrupts rather than changes an index unless the RDB$INDICES row is deleted and re-created in the same transaction. Column name Datatype Length Description RDB$INDEX_NAME CHAR 31 The index associated with this index segment; if the value of this column changes, the RDB$INDEX_NAME column in RDB$INDICES must also be changed RDB$FIELD_NAME CHAR 31 The index segment being defined; the value of this column must match the value of the RDB$FIELD_NAME column in RDB$RELATION_FIELDS RDB$FIELD_POSITION SMALLINT Position of the index segment being defined; corresponds to the sort order of the index TABLE 7.16 RDB$INDEX_SEGMENTS RDB$INDICES RDB$INDICES defines the index structures that allow Firebird to locate rows in the database more quickly. Because Firebird provides both simple indexes (a single-key column) and multi-segment indexes (multiple-key columns), each index defined in this table must have corresponding occurrences in the RDB$INDEX_SEGMENTS table. Column name Datatype Length Description RDB$INDEX_NAME CHAR 31 Names the index being defined; if the value of this column changes, change its value in the RDB$INDEX_SEGMENTS table RDB$RELATION_NAME CHAR 31 Names the table associated with this index; the table must be defined in the RDB$RELATIONS table RDB$INDEX_ID SMALLINT Contains an internal identifier for the index being defined; do not write to this column TABLE 7.17 RDB$INDICES 258
RDB$LOG_FILES Column name Datatype Length Description RDB$UNIQUE_FLAG SMALLINT Specifies whether the index allows duplicate values Values: • 0 - allows duplicate values• 1 - does not allow duplicate values Eliminate duplicates before creating a unique index RDB$DESCRIPTION BLOB 80 Subtype Text: User-written description of the index RDB$SEGMENT_COUNT SMALLINT Number of segments in the index; a value of 1 indicates a simple index RDB$INDEX_INACTIVE SMALLINT Indicates whether the index is: • Active (value of 0) • Inactive (value of 1) RDB$INDEX_TYPE SMALLINT Reserved for future use RDB$FOREIGN_KEY CHAR 31 Name of FOREIGN KEY constraint for which the index is implemented RDB$SYSTEM_FLAG SMALLINT Indicates whether the index is: • User-defined (value of 0)• System-defined (value greater than 0) RDB$EXPRESSION_BLR BLOB 80 Subtype BLR: Contains the BLR (Binary Language Representation) for the expression, evaluated by the database at execution time; used for PC semantics RDB$EXPRESSION_SOURCE BLOB 80 Subtype Text: Contains original text source for the column; used for PC semantics RDB$STATISTICS DOUBLE Selectivity factor for the index; the optimizer uses index selectivity, a PRECISION measure of uniqueness for indexed columns, to choose an access strategy for a query TABLE 7.17 RDB$INDICES (continued) RDB$LOG_FILES RDB$LOG_FILES is no longer used. LANGUAGE REFERENCE 259
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$PAGES RDB$PAGES keeps track of each page allocated to the database. Modifying this table in any way corrupts a database. Column name Datatype Length Description RDB$PAGE_NUMBER INTEGER The physically allocated page number RDB$RELATION_ID SMALLINT Identifier number of the table for which this page is allocated RDB$PAGE_SEQUENCE INTEGER The sequence number of this page in the table to other pages allocated for the previously identified table RDB$PAGE_TYPE SMALLINT Describes the type of page; this information is for system use only TABLE 7.18 RDB$PAGES 260
RDB$PROCEDURE_PARAMETERS RDB$PROCEDURE_PARAMETERS RDB$PROCEDURE_PARAMETERS stores information about each parameter for each of a database’s procedures. Column name Datatype Length Description RDB$PARAMETER_NAME CHAR 31 Parameter name RDB$PROCEDURE_NAME CHAR 31 Name of the procedure in which the parameter is used RDB$PARAMETER_NUMBER SMALLINT Parameter sequence number RDB$PARAMETER_TYPE SMALLINT Parameter datatype Values are: • 0 = input• 1 = output RDB$FIELD_SOURCE CHAR 31 Global column name RDB$DESCRIPTION BLOB 80 Subtype Text: User-written description of the parameter RDB$SYSTEM_FLAG SMALLINT Indicates whether the parameter is: • User-defined (value of 0)• System-defined (value greater than 0) TABLE 7.19 RDB$PROCEDURE_PARAMETERS LANGUAGE REFERENCE 261
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$PROCEDURES RDB$PROCEDURES stores information about a database’s stored procedures. Column name Datatype Length Description RDB$PROCEDURE_NAME CHAR 31 Procedure name RDB$PROCEDURE_ID SMALLINT Procedure number RDB$PROCEDURE_INPUTS SMALLINT Number of input parameters PROCEDURE_OUTPUTS SMALLINT Number of output parameters RDB$DESCRIPTION BLOB 80 Subtype Text: User-written description of the procedure RDB$PROCEDURE_SOURCE BLOB 80 Subtype Text: Source code for the procedure RDB$PROCEDURE_BLR BLOB 80 Subtype BLR: BLR (Binary Language Representation) of the procedure source RDB$SECURITY_CLASS CHAR 31 Security class of the procedure RDB$OWNER_NAME CHAR 31 User who created the procedure (the owner for SQL security purposes) RDB$RUNTIME BLOB 80 Subtype Summary: Describes procedure metadata; used for performance enhancement RDB$SYSTEM_FLAG SMALLINT Indicates whether the procedure is: • User-defined (value of 0)• System-defined (value greater than 0) TABLE 7.20 RDB$PROCEDURES 262
RDB$REF_CONSTRAINTS RDB$REF_CONSTRAINTS RDB$REF_CONSTRAINTS stores referential integrity constraint information. Column name Datatype Length Description RDB$CONSTRAINT_NAME CHAR 31 Name of a referential constraint RDB$CONST_NAME_UQ CHAR 31 Name of a referenced PRIMARY KEY or UNIQUE constraint RDB$MATCH_OPTION CHAR 7 Reserved for later use; currently defaults to FULL RDB$UPDATE_RULE CHAR 11 Specifies the type of action on the foreign key when the primary key is updated; values are NO ACTION, CASCADE, SET NULL, or SET DEFAULT RDB$DELETE_RULE CHAR 11 Specifies the type of action on the foreign key when the primary key is DELETED; values are NO ACTION, CASCADE, SET NULL, or SET DEFAULT TABLE 7.21 RDB$REF_CONSTRAINTS RDB$RELATION_CONSTRAINTS RDB$RELATION_CONSTRAINTS stores information about integrity constraints for tables. Column name Datatype Length Description RDB$CONSTRAINT_NAME CHAR 31 Name of a table constraint RDB$CONSTRAINT_TYPE CHAR 11 Type of table constraint Constraint types are: RIMARY KEY PCHECK UNIQUE NOT NULL FOREIGN KEY RDB$RELATION_NAME CHAR 31 Name of the table for which the constraint is defined RDB$DEFERRABLE CHAR 3 Reserved for later use; currently defaults to No RDB$INITIALLY_DEFERRED CHAR 3 Reserved for later use; currently defaults to No RDB$INDEX_NAME CHAR 31 Name of the index used by UNIQUE, PRIMARY KEY, or FOREIGN KEY constraints TABLE 7.22 RDB$RELATION_CONSTRAINTS LANGUAGE REFERENCE 263
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$RELATION_FIELDS For database tables, RDB$RELATION_FIELDS lists columns and describes column characteristics for domains. SQL columns are defined in RDB$RELATION_FIELDS. The column name is correlated in the RDB$FIELD_SOURCE column to an underlying entry in RDB$FIELDS that contains a system name (“SQL$<n>”). This entry includes information such as column type and length. For both domains and simple columns, this table may contain default and nullability information. Column name Datatype Length Description RDB$FIELD_NAME CHAR 31 Name of the column whose characteristics being defined; the combination of the values in this column and in the RDB$RELATION_NAME column in this table must be unique RDB$RELATION_NAME CHAR 31 Table to which a particular column belongs; a table with this name must appear in RDB$RELATIONS The combination of the values in this column and in the RDB$FIELD_NAMES column in this table must be unique RDB$FIELD_SOURCE CHAR 31 The name for this column in the RDB$FIELDS table; if the column is based on a domain, contains the domain name RDB$QUERY_NAME CHAR 31 Alternate column name for use in isql; supersedes the value in RDB$FIELDS RDB$BASE_FIELD CHAR 31 Views only: The name of the column from RDB$FIELDS in a table or view that is the base for a view column being defined; for the base column: • RDB$BASE_FIELD provides the column name • RDB$VIEW_CONTEXT, a column in this table, provides the source table name RDB$EDIT_STRING VARCHAR 125 Not used in SQL RDB$FIELD_POSITION SMALLINT The position of the column in relation to other columns: • isql obtains the ordinal position for displaying column values when printing rows from this column • gpre uses the column order for SELECT and INSERT statementsIf two or more columns in the same table have the same value for this column, those columns appear in random order RDB$QUERY_HEADER BLOB 80 Not used in SQL TABLE 7.23 RDB$RELATION_FIELDS 264
RDB$RELATION_FIELDS Column name Datatype Length Description RDB$UPDATE_FLAG SMALLINT Not used by Firebird; included for compatibility with other DSRI-based systems RDB$FIELD_ID SMALLINT Identifier for use in BLR (Binary Language Representation) to name the column • Because this identifier changes during backup and restoration of the database, try to use it in transient requests only • Do not modify this column RDB$VIEW_CONTEXT SMALLINT Alias used to qualify view columns by specifying the table location of the base column; it must have the same value as the alias used in the view BLR (Binary Language Representation) for this context stream RDB$DESCRIPTION BLOB 80 Subtype Text: User-written description of the column being defined RDB$DEFAULT_VALUE BLOB 80 Subtype BLR: BLR (Binary Language Representation) for default clause RDB$SYSTEM_FLAG SMALLINT Indicates whether the column is: • User-defined (value of 0)• System-defined (value greater than 0) RDB$SECURITY_CLASS CHAR 31 Names a security class defined in the RDB$SECURITY_CLASSES table; the access restrictions defined by this security class apply to all users of this column RDB$COMPLEX_NAME CHAR 31 Reserved for future use RDB$NULL_FLAG SMALLINT Indicates whether the column may contain NULLs RDB$DEFAULT_SOURCE BLOB 80 Subtype Text: SQL source to define defaults RDB$COLLATION_ID SMALLINT Unique identifier for the collation sequence TABLE 7.23 RDB$RELATION_FIELDS (continued) LANGUAGE REFERENCE 265
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$RELATIONS RDB$RELATIONS defines some of the characteristics of tables and views. Other characteristics, such as the columns included in the table and a description of each column, are stored in the RDB$RELATION_FIELDS table. Column name Datatype Length Description RDB$VIEW_BLR BLOB 80 Subtype BLR: For a view, contains the BLR (Binary Language Representation) of the query Firebird evaluates at the time of execution RDB$VIEW_SOURCE BLOB 80 Subtype Text: For a view, contains the original source query for the view definition RDB$_DESCRIPTION BLOB 80 Subtype Text: Contains a user-written description of the table being defined RDB$RELATION_ID SMALLINT Contains the internal identification number used in BLR (Binary Language Representation) requests; do not modify this column RDB$SYSTEM_FLAG SMALLINT Indicates the contents of a table, either: • User-data (value of 0)• System information (value greater than 0)Do not set this column to 1 when creating tables RDB$DBKEY_LENGTH SMALLINT Length of the database key Values are: • For tables: 8• For views: 8 times the number of tables referenced in the view definition Do not modify the value of this column RDB$FORMAT SMALLINT For Firebird internal use only; do not modify RDB$FIELD_ID SMALLINT The number of columns in the table; this column is maintained by Firebird: do not modify the value of this column RDB$RELATION_NAME CHAR 31 The unique name of the table defined by this row TABLE 7.24 RDB$RELATIONS 266
RDB$ROLES Column name Datatype Length Description RDB$SECURITY_CLASS CHAR 31 Security class defined in the RDB$SECURITY_CLASSES table; access controls defined in the security class apply to all uses of this table RDB$EXTERNAL_FILE VARCHAR 253 • The file in which the external table is stored • If this is blank, the table does not correspond to an external file RDB$RUNTIME BLOB 80 Subtype Summary: Describes table metadata; used for performance enhancement RDB$EXTERNAL_DESCRIPTION BLOB 80 Subtype EXTERNAL_FILE_DESCRIPTION; user-written description of the external file RDB$OWNER_NAME CHAR 31 Identifies the creator of the table or view; the creator is considered the owner for SQL security (GRANT/REVOKE) purposes RDB$DEFAULT_CLASS CHAR 31 Default security class that Firebird applies to columns newly added to a table using the SQL security system RDB$FLAGS SMALLINT TABLE 7.24 RDB$RELATIONS (continued) RDB$ROLES RDB$roles lists roles that have been defined in the database and the owner of each role. Column name Datatype Length Description RDB$ROLE_NAME CHAR 31 Name of role being defined RDB$OWNER_NAME CHAR 31 Name of Firebird user who is creating the role TABLE 7.25 RDB$ROLES LANGUAGE REFERENCE 267
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$SECURITY_CLASSES RDB$SECURITY_CLASSES defines access control lists and associates them with databases, tables, views, and columns in tables and views. For all SQL objects, the information in this table is duplicated in the RDB$USER_PRIVILEGES system table. Column name Datatype Length Description RDB$SECURITY_CLASS CHAR 31 Security class being defined; if the value of this column changes, change its name in the RDB$SECURITY_CLASS column in RDB$_DATABASE, RDB$RELATIONS, and RDB$RELATION_FIELDS RDB$ACL BLOB 80 Subtype ACL: Access control list that specifies users and the privileges granted to those users RDB$DESCRIPTION BLOB 80 Subtype Text: User-written description of the security class being defined TABLE 7.26 RDB$SECURITY_CLASSES RDB$TRANSACTIONS RDB$TRANSACTIONS keeps track of all multi-database transactions. Column name Datatype Length Description RDB$TRANSACTION_ID INTEGER Identifies the multi-database transaction being described RDB$TRANSACTION_STATE SMALLINT Indicates the state of the transaction Valid values are: • 0 - limbo• 1 - committed• 2 - rolled back RDB$TIMESTAMP DATE Reserved for future use RDB$TRANSACTION_DESCRIPTION BLOB 80 Subtype TRANSACTION_DESCRIPTION; describes a prepared multi-database transaction, available if the reconnect fails TABLE 7.27 RDB$TRANSACTIONS 268
RDB$TRIGGER_MESSAGES RDB$TRIGGER_MESSAGES RDB$TRIGGER_MESSAGES defines a trigger message and associates the message with a particular trigger. Column name Datatype Length Description RDB$TRIGGER_NAME CHAR 31 Names the trigger associated with this trigger message; the trigger name must exist in RDB$TRIGGERS RDB$MESSAGE_NUMBER SMALLINT The message number of the trigger message being defined; the maximum number of messages is 32,767 RDB$MESSAGE VARCHAR 78 The source for the trigger message TABLE 7.28 RDB$TRIGGER_MESSAGES RDB$TRIGGERS RDB$TRIGGERS defines triggers. Column name Datatype Length Description RDB$TRIGGER_NAME CHAR 31 Names the trigger being defined RDB$RELATION_NAME CHAR 31 Name of the table associated with the trigger being defined; this name must exist in RDB$RELATIONS RDB$TRIGGER_SEQUENCE SMALLINT Sequence number for the trigger being defined; determines when a trigger is executed in relation to others of the same type • Triggers with the same sequence number execute in alphabetic order by trigger name • If this number is not assigned by the user, Firebird assigns a value of 0 TABLE 7.29 RDB$TRIGGERS LANGUAGE REFERENCE 269
CHAPTER 7 SYSTEM TABLES AND VIEWS Column name Datatype Length Description RDB$TRIGGER_TYPE SMALLINT The type of trigger being defined Values are: • 1 - BEFORE INSERT• 2 - AFTER INSERT• 3 - BEFORE UPDATE• 4 - AFTER UPDATE• 5 - BEFORE DELETE• 6 - AFTER DELETE RDB$TRIGGER_SOURCE BLOB 80 Subtype Text: Original source of the trigger definition; the isql SHOW TRIGGERS statement displays information from this column RDB$TRIGGER_BLR BLOB 80 Subtype BLR: BLR (Binary Language Representation) of the trigger source RDB$DESCRIPTION BLOB 80 Subtype Text: User-written description of the trigger being defined; when including a comment in a CREATE TRIGGER or ALTER TRIGGER statement, isql writes to this column RDB$TRIGGER_INACTIVE SMALLINT Indicates whether the trigger being defined is: • Active (value of 0) • Inactive (value of 1) RDB$SYSTEM_FLAG SMALLINT Indicates whether the trigger is: • User-defined (value of 0)• System-defined (value greater than 0) RDB$FLAGS SMALLINT TABLE 7.29 RDB$TRIGGERS (continued) 270
RDB$TYPES RDB$TYPES RDB$TYPES records enumerated datatypes and alias names for Firebird character sets and collation orders. This capability is not available in the current release. Column name Datatype Length Description RDB$FIELD_NAME CHAR 31 Column for which the enumerated datatype is being defined RDB$TYPE SMALLINT Identifies the internal number that represents the column specified above; type codes (same as RDB$DEPENDENT_TYPES): • 0 - table• 1 - view• 2 - trigger• 3 - computed_field• 4 - validation• 5 - procedure All other values are reserved for future use RDB$TYPE_NAME CHAR 31 Text that corresponds to the internal number RDB$DESCRIPTION BLOB 80 Subtype Text: Contains a user-written description of the enumerated datatype being defined RDB$SYSTEM_FLAG SMALLINT Indicates whether the datatype is: • User-defined (value of 0)• System-defined (value greater than 0) TABLE 7.30 RDB$TYPES LANGUAGE REFERENCE 271
CHAPTER 7 SYSTEM TABLES AND VIEWS RDB$USER_PRIVILEGES RDB$USER_PRIVILEGES keeps track of the privileges assigned to a user through an SQL GRANT statement. There is one occurrence of this table for each user/privilege intersection. Column name Datatype Length Description RDB$USER CHAR 31 Names the user who was granted the privilege listed in the RDB$PRIVILEGE column RDB$GRANTOR CHAR 31 Names the user who granted the privilege RDB$PRIVILEGE CHAR 6 Identifies the privilege granted to the user listed in the RDB$USER column, above Valid values are: • ALL• SELECT• DELETE• INSERT• UPDATE• REFERENCE• MEMBER OF (for roles) RDB$GRANT_OPTION SMALLINT Indicates whether the privilege was granted with the WITH GRANT OPTION (value of 1) or not (value of 0) RDB$RELATION_NAME CHAR 31 Identifies the table to which the privilege applies RDB$FIELD_NAME CHAR 31 For update privileges, identifies the column to which the privilege applies RDB$USER_TYPE SMALLINT RDB$OBJECT_TYPE SMALLINT TABLE 7.31 RDB$USER_PRIVILEGES 272
RDB$VIEW_RELATIONS RDB$VIEW_RELATIONS RDB$VIEW_RELATIONS is not used by SQL objects. Column name Datatype Length Description RDB$VIEW_NAME CHAR 31 Name of a view: The combination of RDB$VIEW_NAME and RDB$VIEW_CONTEXT must be unique RDB$RELATION_NAME CHAR 31 Name of a table referenced in the view definition RDB$VIEW_CONTEXT SMALLINT Alias used to qualify view columns; must have the same value as the alias used in the view BLR (Binary Language Representation) for this query RDB$CONTEXT_NAME CHAR 31 Textual version of the alias identified in RDB$VIEW_CONTEXT This variable must: • Match the value of the RDB$VIEW_SOURCE column for the corresponding table in RDB$RELATIONS • Be unique in the view TABLE 7.32 RDB$VIEW_RELATIONS System views You can create an SQL script using the code provided in this section to create four views that provide information about existing integrity constraints for a database. You must create the database prior to creating these views. SQL system views are a subset of system views defined in the SQL-92 standard. Since they are defined by ANSI SQL-92, the names of the system views and their columns do not start with RDB$. g The CHECK_CONSTRAINTS view CREATE VIEW CHECK_CONSTRAINTS ( CONSTRAINT_NAME, CHECK_CLAUSE ) AS SELECT RDB$CONSTRAINT_NAME, RDB$TRIGGER_SOURCE FROM RDB$CHECK_CONSTRAINTS RC, RDB$TRIGGERS RT WHERE RT.RDB$TRIGGER_NAME = RC.RDB$TRIGGER_NAME; g The CONSTRAINTS_COLUMN_USAGE view CREATE VIEW CONSTRAINTS_COLUMN_USAGE ( LANGUAGE REFERENCE 273
CHAPTER 7 SYSTEM TABLES AND VIEWS TABLE_NAME, COLUMN_NAME, CONSTRAINT_NAME ) AS SELECT RDB$RELATION_NAME, RDB$FIELD_NAME, RDB$CONSTRAINT_NAME FROM RDB$RELATION_CONSTRAINTS RC, RDB$INDEX_SEGMENTS RI WHERE RI.RDB$INDEX_NAME = RC.RDB$INDEX_NAME; g The REFERENTIAL_CONSTRAINTS view CREATE VIEW REFERENTIAL_CONSTRAINTS ( CONSTRAINT_NAME, UNIQUE_CONSTRAINT_NAME, MATCH_OPTION, UPDATE_RULE, DELETE_RULE ) AS SELECT RDB$CONSTRAINT_NAME, RDB$CONST_NAME_UQ, RDB$MATCH_OPTION, RDB$UPDATE_RULE, RDB$DELETE_RULE FROM RDB$REF_CONSTRAINTS; g The TABLE_CONSTRAINTS view CREATE VIEW TABLE_CONSTRAINTS ( CONSTRAINT_NAME, TABLE_NAME, CONSTRAINT_TYPE, IS_DEFERRABLE, INITIALLY_DEFERRED ) AS SELECT RDB$CONSTRAINT_NAME, RDB$RELATION_NAME, RDB$CONSTRAINT_TYPE, RDB$DEFERRABLE, RDB$INITIALLY_DEFERRED FROM RDB$RELATION_CONSTRAINTS; 274
CHECK_CONSTRAINTS CHECK_CONSTRAINTS CHECK_CONSTRAINTS identifies all CHECK constraints defined in the database. Column name Datatype Length Description CONSTRAINT_NAME CHAR 31 Unique name for the CHECK constraint; nullable CHECK_CLAUSE BLOB 80 Subtype Text: Nullable; original source of the trigger definition, stored in the RDB$TRIGGER_SOURCE COLUMN in RDB$TRIGGERS TABLE 7.33 CHECK_CONSTRAINTS CONSTRAINTS_COLUMN_USAGE CONSTRAINTS_COLUMN_USAGE identifies columns used by PRIMARY KEY and UNIQUE constraints. For FOREIGN KEY constraints, this view identifies the columns defining the constraint. Column name Datatype Length Description TABLE_NAME CHAR 31 Table for which the constraint is defined; nullable COLUMN_NAME CHAR 31 Column used in the constraint definition; nullable CONSTRAINT_NAME CHAR 31 Unique name for the constraint; nullable TABLE 7.34 CONSTRAINTS_COLUMN_USAGE LANGUAGE REFERENCE 275
CHAPTER 7 SYSTEM TABLES AND VIEWS REFERENTIAL_CONSTRAINTS REFERENTIAL_CONSTRAINTS identifies all referential constraints defined in a database. Column name Datatype Length Description CONSTRAINT_NAME CHAR 31 Unique name for the constraint; nullable UNIQUE_CONSTRAINT_NAME CHAR 31 Name of the UNIQUE or PRIMARY KEY constraint corresponding to the specified referenced column list; nullable MATCH_OPTION CHAR 7 Reserved for future use; always set to FULL; nullable UPDATE_RULE CHAR 11 Reserved for future use; always set to RESTRICT; nullable DELETE_RULE CHAR 11 Reserved for future use; always set to RESTRICT; nullable TABLE 7.35 REFERENTIAL_CONSTRAINTS TABLE_CONSTRAINTS TABLE_CONSTRAINTS identifies all constraints defined in a database. Column name Datatype Length Description CONSTRAINT_NAME CHAR 31 Unique name for the constraint; nullable TABLE_NAME CHAR 31 Table for which the constraint is defined; nullable CONSTRAINT_TYPE CHAR 11 Possible values are UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK; nullable IS_DEFERRABLE CHAR 3 Reserved for future use; always set to No; nullable INITIALLY_DEFERRED CHAR 3 Reserved for future use; always set to No; nullable TABLE 7.36 TABLE_CONSTRAINTS 276
CHAPTER 8 Character Sets and Chapter 8 Collation Orders CHAR, VARCHAR, and text Blob columns in Firebird can use many different character sets. A character set defines the symbols that can be entered as text in a column, and its also defines the maximum number of bytes of storage necessary to represent each symbol. In some character sets, such as ISO8859_1, each symbol requires only a single byte of storage. In others, such as UNICODE_FSS, each symbol requires from 1 to 3 bytes of storage. Each character set also has an implicit collation order that specifies how its symbols are sorted and ordered. Some character sets also support alternative collation orders. In all cases, choice of character set limits choice of collation orders. This chapter lists available character sets and their corresponding collation orders and describes how to specify: g Default character set for an entire database g Alternative character set and collation order for a particular column in a table g Client application character set that the server should use when translating data between itself and the client g Collation order for a value in a comparison operation g Collation order in an ORDER BY or GROUP BY clause LANGUAGE REFERENCE 277
CHAPTER 8 CHARACTER SETS AND COLLATION ORDERS Firebird character sets and collation orders The following table lists each character set that can be used in Firebird. For each character set, the minimum and maximum number of bytes used to store each character is listed, and all collation orders supported for that character set are also listed. The first collation order for a given character set is that set’s default collation, the one that is used if no COLLATE clause specifies an alternative order. Character Char. Max. Min. set set ID char. size char. size Collation orders ASCII 2 1 byte 1 byte ASCII BIG_5 56 2 bytes 1 byte BIG_5 CYRL 50 1 byte 1 byte CYRLDB_RUSPDOX_CYRL DOS437 10 1 byte 1 byte DOS437DB_DEU437DB_ESP437DB_FIN437DB_FRA437DB_ITA437DB_NLD437DB_SVE437DB_UK437DB_US437PDOX_ASCIIPDOX_INTLPDOX_SWEDFIN DOS850 11 1 byte 1 byte DOS850DB_DEU850DB_ESP850DB_FRA850DB_FRC850DB_ITA850DB_NLD850DB_PTB850DB_SVE850DB_UK850DB_US850 TABLE 8.1 Character sets and collation orders 278
Firebird CHARACTER SETS AND COLLATION ORDERS Character Char. Max. Min. set set ID char. size char. size Collation orders DOS852 45 1 byte 1 byte DOS852DB_CSYDB_PLKDB_SLOPDOX_CSYPDOX_HUNPDOX_PLKPDOX_SLO DOS857 46 1 byte 1 byte DOS857DB_TRK DOS860 13 1 byte 1 byte DOS860DB_PTG860 DOS861 47 1 byte 1 byte DOS861PDOX_ISL DOS863 14 1 byte 1 byte DOS863DB_FRC863 DOS865 12 1 byte 1 byte DOS865DB_DAN865DB_NOR865PDOX_NORDAN4 EUCJ_0208 6 2 bytes 1 byte EUJC_0208 GB_2312 57 2 bytes 1 byte GB_2312 TABLE 8.1 Character sets and collation orders (continued) LANGUAGE REFERENCE 279
CHAPTER 8 CHARACTER SETS AND COLLATION ORDERS Character Char. Max. Min. set set ID char. size char. size Collation orders ISO8859_1 21 1 byte 1 byte ISO8859_1DA_DADE_DEDU_NLEN_UKEN_USES_ESFI_FIFR_CAFR_FRIS_ISIT_ITNO_NOPT_PTSV_SV KSC_5601 44 2 bytes 1 byte KSC_5601KSC_DICTIONARY NEXT 19 1 byte 1 byte NEXTNXT_DEUNXT_FRANXT_ITANXT_US NONE 0 1 byte 1 byte NONE OCTETS 1 1 byte 1 byte OCTETS SJIS_0208 5 2 bytes 1 byte SJIS_0208 UNICODE_FSS 3 3 bytes 1 byte UNICODE_FSS TABLE 8.1 Character sets and collation orders (continued) 280
Firebird CHARACTER SETS AND COLLATION ORDERS Character Char. Max. Min. set set ID char. size char. size Collation orders WIN1250 51 1 byte 1 byte WIN1250PXW_CSYPXW_HUNDCPXW_PLKPXW_SLO WIN1251 52 1 byte 1 byte WIN1251PXW_CYRL WIN1252 53 1 byte 1 byte WIN1252PXW_INTLPXW_INTL850PXW_NORDAN4PXW_SPANPXW_SWEDFIN WIN1253 54 1 byte 1 byte WIN1253PXW_GREEK WIN1254 55 1 byte 1 byte WIN1254PXW_TURK TABLE 8.1 Character sets and collation orders (continued) Character set storage requirements Knowing the storage requirements of a particular character set is important, because in the case of CHAR columns, Firebird restricts the maximum amount of storage in each field in the column to 32,767 bytes (VARCHAR is restricted to 32,765 bytes). For character sets that require only a single byte of storage, the maximum number of symbols that can be stored in a single field corresponds to the number of bytes. For character sets that require up to three bytes per symbol, the maximum number of symbols that can be safely stored in a field is 1/3 of the maximum number of bytes for the datatype. For example, for a CHAR column defines to use the UNICODE_FSS character set, the maximum number of characters that can be specified is 10,922 (32,767/3): . . . CHAR(10922) CHARACTER SET UNICODE_FSS, . . . LANGUAGE REFERENCE 281
CHAPTER 8 CHARACTER SETS AND COLLATION ORDERS 4 Character sets for Microsoft Windows There are five character sets that support Windows client applications, such as Paradox for Windows. These character sets are WIN1250, WIN1251, WIN1252, WIN1253, and WIN1254. 282
SPECIFYING CHARACTER SETS The names of collation orders for these character sets that are specific to Paradox for Windows begin “PXW”. For example, the WIN1252 character set supports a Paradox for Windows collation order for Norwegian and Danish called “PXW_NORDAN4”. For more information about Windows character sets and Paradox for Windows collation orders, see the appropriate Paradox for Windows documentation and driver books. Additional character sets and collations Support for additional character sets and collation orders is constantly being added to Firebird. To see if additional character sets and collations are available for a newly created database, connect to the database with isql, then use the following set of queries to generate a list of available character sets and collations: SELECT RDB$CHARACTER_SET_NAME, RDB$CHARACTER_SET_ID FROM RDB$CHARACTER_SETS ORDER BY RDB$CHARACTER_SET_NAME; SELECT RDB$COLLATION_NAME, RDB$CHARACTER_SET_ID FROM RDB$COLLATIONS ORDER BY RDB$COLLATION_NAME; Specifying character sets This section provides details on how to specify character sets. Specifically, it covers how to specify the following: g The default character set for a database g A character set for a table column g The character set for a client attachment g The collation order for a column g The collation order in comparisons g The collation order for ORDER BY and GROUP BY clauses LANGUAGE REFERENCE 283
CHAPTER 8 CHARACTER SETS AND COLLATION ORDERS Default character set for a database A database’s default character set designation specifies the character set the server uses to tag CHAR, VARCHAR, and text Blob columns in the database when no other character set information is provided. When data is stored in such columns without additional character set information, the server uses the tag to determine how to store and transliterate that data. A default character set should always be specified for a database when it is created with CREATE DATABASE. To specify a default character set, use the DEFAULT CHARACTER SET clause of CREATE DATABASE. For example, the following statement creates a database that uses the ISO8859_1 character set: CREATE DATABASE ’europe.fdb’ DEFAULT CHARACTER SET ISO8859_1; IMPORTANT If you do not specify a character set, the character set defaults to NONE. Using character set NONE means that there is no character set assumption for columns; data is stored and retrieved just as you originally entered it. You can load any character set into a column defined with NONE, but you cannot later move that data into another column that has been defined with a different character set. In this case, no transliteration is performed between the source and destination character sets, and errors may occur during assignment. For the complete syntax of CREATE DATABASE, see CREATE DATABASE on page 49. Character set for a column in a table Character sets for individual columns in a table can be specified as part of the column’s CHAR or VARCHAR datatype definition. When a character set is defined at the column level, it overrides the default character set declared for the database. For example, the following isql statements create a database with a default character set of ISO8859_1, then create a table where two column definitions include a different character set specification: CREATE DATABASE ’europe.fdb’ DEFAULT CHARACTER SET ISO8859_1; CREATE TABLE RUS_NAME( LNAME VARCHAR(30) NOT NULL CHARACTER SET CYRL, FNAME VARCHAR(20) NOT NULL CHARACTER SET CYRL, ); For the complete syntax of CREATE TABLE, see CREATE TABLE on page 72. 284
SPECIFYING CHARACTER SETS Character set for a client attachment When a client application, such as isql, connects to a database, it may have its own character set requirements. The server providing database access to the client does not know about these requirements unless the client specifies them. The client application specifies its character set requirement using the SET NAMES statement before it connects to the database. SET NAMES specifies the character set the server should use when translating data from the database to the client application. Similarly, when the client sends data to the database, the server translates the data from the client’s character set to the database’s default character set (or the character set for an individual column if it differs from the database’s default character set). For example, the following isql command specifies that isql is using the DOS437 character set. The next command connects to the europe database created above, in “Specifying a Character Set for a Column in a Table”: SET NAMES DOS437; CONNECT ’europe.fdb’ USER ’JAMES’ PASSWORD ’U4EEAH’; For the complete syntax of SET NAMES, see SET NAMES on page 149. For the complete syntax of CONNECT, see CONNECT on page 44. Collation order for a column When a CHAR or VARCHAR column is created for a table, either with CREATE TABLE or ALTER TABLE, the collation order for the column can be specified using the COLLATE clause. COLLATE is especially useful for character sets such as ISO8859_1 or DOS437 that support many different collation orders. For example, the following isql ALTER TABLE statement adds a new column to a table, and specifies both a character set and a collation order: ALTER TABLE ’FR_CA_EMP’ ADD ADDRESS VARCHAR(40) CHARACTER SET ISO8859_1 NOT NULL COLLATE FR_CA; For the complete syntax of ALTER TABLE, see ALTER TABLE on page 28. LANGUAGE REFERENCE 285
CHAPTER 8 CHARACTER SETS AND COLLATION ORDERS Collation order in comparison When CHAR or VARCHAR values are compared in a WHERE clause, it can be necessary to specify a collation order for the comparisons if the values being compared use different collation orders. To specify the collation order to use for a value during a comparison, include a COLLATE clause after the value. For example, in the following WHERE clause fragment from an embedded application, the value to the left of the comparison operator is forced to be compared using a specific collation: WHERE LNAME COLLATE FR_CA = :lname_search; For the complete syntax of the WHERE clause, see SELECT on page 139. Collation order in ORDER BY When CHAR or VARCHAR columns are ordered in a SELECT statement, it can be necessary to specify a collation order for the ordering, especially if columns used for ordering use different collation orders. To specify the collation order to use for ordering a column in the ORDER BY clause, include a COLLATE clause after the column name. For example, in the following ORDER BY clause, the collation order for two columns is specified: . . . ORDER BY LNAME COLLATE FR_CA, FNAME COLLATE FR_CA; For the complete syntax of the ORDER BY clause, see SELECT on page 139. Collation order in a GROUP BY clause When CHAR or VARCHAR columns are grouped in a SELECT statement, it can be necessary to specify a collation order for the grouping, especially if columns used for grouping use different collation orders. To specify the collation order to use for grouping columns in the GROUP BY clause, include a COLLATE clause after the column name. For example, in the following GROUP BY clause, the collation order for two columns is specified: . . . GROUP BY LNAME COLLATE FR_CA, FNAME COLLATE FR_CA; For the complete syntax of the GROUP BY clause, see SELECT on page 139. 286
APPENDIX A Firebird DOCUMENT CONVENTIONS Syntax conventions The following table lists the conventions used in syntax statements and sample code, and provides examples of their use: Convention Purpose Example UPPERCASE Keywords that must be typed exactly as •SET TERM !!; they appear when used •ADD [CONSTRAINT] CHECK italic User-supplied parameters that cannot be •CREATE TRIGGER name FOR table;broken into smaller units •ALTER EXCEPTION name 'message' <italic> Parameters in angle brackets can be WHILE (<condition>) DO <compound_statement> broken into smaller syntactic units; the expansion syntax for these parameters follows the current syntax statement [ ] Optional syntax: you do not need to •CREATE [UNIQUE][ASCENDING | DESCENDING] include anything that is enclosed in •[FILTER [FROM subtype] TO subtype] square brackets; when elements within these brackets are separated by the pipe symbol (|), you can choose only one { } You must include one and only one of the {INTO | USING}enclosed options, which are separated by the pipe symbol (|) | You can choose only one of a group whose SELECT [DISTINCT | ALL]elements are separated by this pipe symbol ... You can repeat the clause enclosed in (<col> [,<col>…]) brackets with the “…” symbol as many times as necessary TABLE A.3 Syntax conventions 290
Index ; (semicolon), terminator 162 exiting 169 BEGIN DECLARE SECTION 39 BLOB cursors A closing 41 access privileges See security declaring 92 active set (cursors) 132 inserting data 129 adding opening 132 See also inserting BLOB data columns 28 converting subtypes 96 integrity constraints 28 inserting 92, 129 secondary files 22 selecting 92 aggregate functions 18 updating 158 AVG() 37 BLOB data type 277 COUNT() 48 BLOB filters MAX() 130 declaring 95 MIN() 131 dropping 106 SUM() 156 viewing information about 254 ALTER DATABASE 22 BLOB segments ALTER DOMAIN 23 host-language variables 38 ALTER EXCEPTION 25 retrieving 121 ALTER INDEX 26 ALTER PROCEDURE 27 ALTER TABLE 28 C ALTER TRIGGER 35 CACHE option 46 applications cache size, changing 46 preprocessing See gpre case, converting 158 arithmetic functions See aggregate functions CAST() 39 arrays casting 39 See also error status array CHAR data type 277 viewing dimension information 248 CHAR datatype assigning values to variables 163 description 19 assignment statements 163 CHAR VARYING keyword 20 averages 36 CHARACTER keyword 19 AVG() 36 CHARACTER SET default 51 domains 54 B specifying 149 BASED ON 38 tables 76 BEGIN . . . END block character sets 277–286 defined 163, 164 LANGUAGE REFERENCE i
additional 283 constraints default 284 See also integrity constraints retrieving 283 adding 28, 77 specifying 284–285 dropping 28 table of 278 types 77 character strings, converting case 158 viewing information about 263, 276 CHARACTER VARYING keyword 20 CONSTRAINTS_COLUMN_USAGE system CHECK constraints 78 view 275 viewing information about 244, 275 context variables 173–174 CHECK_CONSTRAINTS conversion functions 18 system view 275 UPPER() 158 clients See SQL client applications; Windows converting clients case 158 CLOSE 40 datatypes 39 CLOSE (BLOB) 41 COUNT() 48 code lines, terminating 162 CREATE DATABASE 49 code pages (MS-DOS) 282 CREATE DOMAIN 52 COLLATE clause CREATE EXCEPTION 57 domains 55 CREATE GENERATOR 58 tables 76 CREATE INDEX 59 collation orders 277 CREATE PROCEDURE 61, 162 retrieving 283 CREATE ROLE 69 specifying 76, 285–287 CREATE SHADOW 69 viewing information about 244 CREATE TABLE 72 columns CREATE TRIGGER 80, 162 adding 28 CREATE VIEW 87 computed 76 creating defining 52, 76 UDFs 189 domain-based 76 creating multi-file databases 22 dropping 28 cursors formatting 254 active set 132 index characteristics 258 closing 40 inheritable characteristics 55 declaring 90 local 76 opening 132 specifying character sets 284 retrieving data 119 viewing characteristics of 248, 254, 264 comments in stored procedures and triggers 165 COMMIT D 42 compound statements 163 data computed columns 76 inserting 127 conditional statements 171, 182 retrieving 119 conditions, testing 171, 182 selecting 139, 176 See also search conditions sorting 277 CONNECT 44 storing 277 connecting to databases 44 updating 156 data integrity ii
adding constraints 28, 77 tables 97 dropping constraints 28 default character set 284 database cache buffers default transactions 153 increasing/decreasing 46 defining database handles columns 52, 76 declaring 147 domains 54–55 database objects integrity constraints 77 viewing relationships among 246 DELETE 98, 174 database pages 50 WHERE clause requirement 99 viewing information about 260 deleting See dropping databases DESCRIBE 100 altering 22 DISCONNECT 102 connecting to 44 domain-based columns 76 creating 49 domains declaring scope of 147 altering 23 detaching 102 creating 52 dropping 102 defining 54–55 multi-file 22 dropping 103 setting access to in SQL 146, 150, 155 inheritable characteristics 55 shadowing 69, 109 DOUBLE PRECISION datatype 19 viewing information about 276 DROP DATABASE 102 datatypes 19 DROP DOMAIN 103 converting 39 DROP EXCEPTION 104 in table columns 76 DROP EXTERNAL FUNCTION 105 specifying with domains 52 DROP FILTER 106 DATE datatype DROP INDEX 107 description 19, 20 DROP PROCEDURE 108 dBASE for DOS 282 DROP ROLE 108 dBASE for Windows 282 DROP SHADOW 108, 109 DECIMAL datatype 19 DROP TABLE 110 DECLARE CURSOR 20, 40, 90, 91 DROP TRIGGER 111 DECLARE CURSOR (BLOB) 92 DROP VIEW 112 DECLARE EXTERNAL FUNCTION 93, 189, 190 dropping DECLARE FILTER 95 columns 28 DECLARE STATEMENT 20, 40, 90, 91, 97 integrity constraints 28 DECLARE TABLE 20, 40, 76, 90, 91, 97 rows 98 DECLARE VARIABLE 166 DSQL statements declaring declaring table structures 97 database handles 147 executing 115, 117 error status array 201 preparing 133 host-language variables 38–39, 112 local variables 166 scope of databases E 147 SQL statements 97 -either_case switch 134 SQLCODE variable 39 END DECLARE SECTION 112 error codes 199–240 LANGUAGE REFERENCE iii
error status array 201 columns 254 declaring 201 functions 18 defined 200 aggregate 18 error codes 221–238 arguments 255 SQLCODE variable conversion 18, 158 error codes and messages 205–220 numeric 18, 122 error-handling routines 20–21, 200–203 user-defined See UDFs options 202 stored procedures 179 triggers G 179 errors GEN_ID() 122 run-time 199 generators trapping 159, 179, 200 creating 58 user-defined See exceptions initializing 148 EVENT INIT 113 resetting, caution 149 EVENT WAIT 114 returning 122 events viewing information about 257 See also triggers gpre 112 posting 176 declaring SQLCODE automatically 39 registering interest in 113 -either_case switch 134 EXCEPTION 166 error status array processing 201 exceptions 57 -manual switch 102, 153 altering 25 gpre directives creating 57 BASED ON 38 defined 166 BEGIN DECLARE SECTION 39 dropping 104 DECLARE TABLE 97 viewing information about 247 END DECLARE SECTION 112 EXECUTE 115 GRANT 123 EXECUTE IMMEDIATE 117 EXECUTE PROCEDURE 118, 167 H EXIT 169 host-language variables expression-based columns See computed columns declaring 38–39, 112 EXTERNAL FILE option 77 I F I/O See input, output FETCH 119 IF . . . THEN . . . ELSE 171 FETCH (BLOB) 121 indexes files activating/deactivating 26 secondary 22, 253 altering 26 shadow 253 columns comprising 258 FLOAT datatype 19 creating 59 FOR SELECT . . . DO 170 dropping 107 FOREIGN KEY constraints 77 rebalancing 26 viewing information about 275 recomputing selectivity 151 formatting viewing structures of 258 iv
indicator variables 118 L initializing library, UDF 190–198 generators 148 local columns 76 input parameters 62 local variables defined 172 assigning values 163 input statements 101 declaring 166 INSERT 127, 173 loops See repetitive statements INSERT CURSOR (BLOB) 129 lowercase, converting from 158 inserting See also addingnew rows M 127 INTEGER datatype 19 -manual switch 102, 153 integrity constraints MAX() 130 See also specific type maximum values 130 adding 28, 77 messages 199–240 cascading 33, 34, 75, 77, 79 metadata 241 dropping 28 MIN() 131 types 77 minimum values 131 viewing information about 263, 276 modifying See altering;updating Interactive SQL See isql MS-DOS code pages 282 international character sets 277–286 multi-file databases additional 283 creating 22 default 284 multiple transactions specifying 284–285 running 153 isc_convert_error 202 isc_deadlock 202 N isc_integ_fail 202 naming conventions isc_lock_conflict 202 keywords and 183 isc_no_dup 202 nested stored procedures 167 isc_not_valid 202 NEW context variables 173 isc_print_sqlerror() 201 NO RECORD_VERSION 154 isc_sql_interprete() 202 NO WAIT 153 isc_status 201 nomenclature ISOLATION LEVEL 154 stored procedures and triggers 163 isql numbers statements, terminating 162 averaging 36 calculating totals 156 K NUMERIC datatype 19 key constraints See FOREIGN KEY constraints; numeric function 18, 122 PRIMARY KEY constraints numeric values See values keys defined 77 O keywords 183–187 OLD context variables 174 OPEN 131 OPEN (BLOB) 132 LANGUAGE REFERENCE v
output RDB$LOG_FILES 259 error messages 201 RDB$PAGES 260 output parameters 62 RDB$PROCEDURE_PARAMETERS 261 defined 175 RDB$PROCEDURES 262 output statements 101 RDB$REF_CONSTRAINTS 263 RDB$RELATION_CONSTRAINTS 263 RDB$RELATION_FIELDS 264 P RDB$RELATIONS 266 Paradox for DOS 282 RDB$SECURITY_CLASSES 268 Paradox for Windows 282, 283 RDB$TRANSACTIONS 268 parameters RDB$TRIGGER_MESSAGES 269 DSQL statements 100 RDB$TRIGGERS 269 input 62, 172 RDB$TYPES 271 output 62, 175 RDB$USER_PRIVILEGES 272 stored procedures 261 RDB$VIEW_RELATIONS 273 plan, specifying 143, 145 READ COMMITTED 154 plan_expr 141 read-only transactions plan_item 141 committing 43 POST_EVENT 176 read-only views 89 posting events 176 RECORD_VERSION 154 PREPARE 133 recursive stored procedures 168 preprocessor See gpre REFERENCES constraint 77 primary files 50 referential integrity See integrity constraints PRIMARY KEY constraints 58, 77 REFERENTIAL_CONSTRAINTS system view 276 viewing information about 275 RELEASE argument 43 privileges See security repetitive statements 170, 182 procedures See stored procedures repetitive tasks 168 reserved words See keywords R RESERVING clause 154 RDB$CHARACTER_SETS 243 retrieving data 119 RDB$CHECK_CONSTRAINTS 244 REVOKE 135 RDB$COLLATIONS 244 roles RDB$DATABASE 245 creating 69 RDB$DEPENDENCIES 246 dropping 108 RDB$EXCEPTIONS 247 granting 123 RDB$FIELD_DIMENSIONS 248 revoking 135 RDB$FIELDS 248 system table 267 RDB$FILES 253 ROLLBACK 138 RDB$FILTERS 254 rows RDB$FORMATS 254 deleting 98 RDB$FUNCTION_ARGUMENTS 255 inserting 127 RDB$FUNCTIONS 256 selecting 119 RDB$GENERATORS 257 stored procedures and triggers 176 RDB$INDEX_SEGMENTS 258 sequentially accessing 120 RDB$INDICES 258 updating 156 vi
run-time errors 199 error codes and messages 205–220 return values 20 statements 163 S See also DSQL statements; SQL statements search conditions (queries) assignment 163 comparing values 144, 176 compound 163 evaluating 132 conditional 171, 182 secondary files 50 executing 133 adding 22 input/output 101 viewing information about 253 repetitive 170, 182 secondary storage devices 70 SQLCODE and 20 security terminating 162 access privileges 125 status array See error status array granting 123 storage devices revoking 135 secondary 70 viewing 272 stored procedures viewing access control lists 268 adding comments 165 SELECT 139, 176 altering 27 selecting assigning values 163 data 139–144 creating 61, 162 stored procedures and triggers 176 dropping 108 semicolon (;), terminator 162 error handling 179 SET DATABASE 146, 150, 155 executing 118, 167 SET GENERATOR 148 exiting 169 SET NAMES 149, 285 indicator variables 118 SET STATISTICS 151 nested 167 SET TRANSACTION 152 passing values to 172 shadow files posting events 176 sets 70 powerful SQL extensions 161 viewing information about 253 recursive 168 shadows terminating 180 creating 69 viewing information about 247, 261, 262 dropping 109 storing data 277 SMALLINT datatype 19 strings See character strings SNAPSHOT TABLE STABILITY 154 SUM() 156 sorting SUSPEND 177 data 277 system tables 241–273 specifying system views 241, 273–274 collation orders 76, 285–287 SQL clients specifying character sets 285 T SQL statements 17 TABLE_CONSTRAINTS system view 276 declaring 97 tables executing 20 altering 28 SQLCODE variable 20, 200–201 creating 72 declaring automatically 39 declaring 97 LANGUAGE REFERENCE vii
dropping 110 uppercase, converting to 158 inserting rows 127 USER name 75, 78 viewing information about 263, 266, 276 user-defined errors See exceptions tasks, repetitive 168 user-defined functions See UDFs terminators (syntax) 162 USING clause 154 text 277 totals, calculating 156 transaction names V 152 transactions values committing 42 See also NULL values default 153 assigning to variables 163 multiple databases 268 averages 36 read-only 43 changing 172, 173 rolling back 138 maximum 130 running multiple 115, 117, 153 minimum 131 starting 152 passing to stored procedures 172 trapping returning 175, 177 errors 159, 179, 200 to SQLCODE variable 20 warnings 159, 200 totals 156 triggers 163 VARCHAR data type 277 altering 35 VARCHAR datatype 20 creating 80, 162 variables dropping 111 context 173–174 error handling 179 host-language 38–39, 112 message information 269 indicator 118 NEW values 173 local 163, 166 OLD values 174 views posting events 176 creating 87 viewing information about 247, 269 dropping 112 read-only 89 updatable 88 U viewing characteristics of 266 UDF library 190–198 UDFs 189–198, 256 creating W 189 declaring 93 WAIT 153 dropping 105 warnings UNION operator 176 See also errors UNIQUE constraints trapping 159, 200 viewing information about 275 WHEN 57 UNIQUE keys 77 WHEN . . . DO 179 UPDATE 156, 173, 174 WHENEVER 159, 200 updating WHERE clause See SELECT BLOB data 158 WHILE . . . DO 182 rows 156 Windows applications UPPER() 158 character sets 282 viii
Windows clients specifying character sets 285 LANGUAGE REFERENCE ix

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