Edit File: innodb-truncate.result
# # TRUNCATE TABLE # # Truncating is disallowed for parent tables unless such table # participates in self-referencing foreign keys only. # CREATE TABLE t1 (pk INT PRIMARY KEY) ENGINE=INNODB; CREATE TABLE t2 (fk INT NOT NULL, FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB; TRUNCATE TABLE t1; ERROR 42000: Cannot truncate a table referenced in a foreign key constraint (`test`.`t2`, CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`fk`) REFERENCES `test`.`t1` (`pk`)) # Truncation of child should succeed. TRUNCATE TABLE t2; DROP TABLE t2; DROP TABLE t1; CREATE TABLE t1 (pk INT PRIMARY KEY, fk INT, FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB; # Truncation of self-referencing table should succeed. TRUNCATE TABLE t1; DROP TABLE t1; # # Also, truncating such tables is allowed if foreign key # checks are disabled. # SET @old_foreign_key_checks = @@SESSION.foreign_key_checks; CREATE TABLE t1 (pk INT PRIMARY KEY) ENGINE=INNODB; CREATE TABLE t2 (fk INT NOT NULL, FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB; CREATE TABLE t3 (pk INT PRIMARY KEY, fk INT, FOREIGN KEY (fk) REFERENCES t1 (pk)) ENGINE=INNODB; SET @@SESSION.foreign_key_checks = 0; TRUNCATE TABLE t1; TRUNCATE TABLE t2; TRUNCATE TABLE t3; SET @@SESSION.foreign_key_checks = 1; TRUNCATE TABLE t1; ERROR 42000: Cannot truncate a table referenced in a foreign key constraint (`test`.`t2`, CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`fk`) REFERENCES `test`.`t1` (`pk`)) TRUNCATE TABLE t2; TRUNCATE TABLE t3; LOCK TABLES t1 WRITE; SET @@SESSION.foreign_key_checks = 0; TRUNCATE TABLE t1; SET @@SESSION.foreign_key_checks = 1; TRUNCATE TABLE t1; ERROR 42000: Cannot truncate a table referenced in a foreign key constraint (`test`.`t2`, CONSTRAINT `t2_ibfk_1` FOREIGN KEY (`fk`) REFERENCES `test`.`t1` (`pk`)) UNLOCK TABLES; DROP TABLE t3,t2,t1; SET @@SESSION.foreign_key_checks = @old_foreign_key_checks; # # Test that TRUNCATE resets auto-increment. # CREATE TABLE t1 (a INT PRIMARY KEY NOT NULL AUTO_INCREMENT); INSERT INTO t1 VALUES (NULL), (NULL); SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't1'; AUTO_INCREMENT 3 SELECT * FROM t1 ORDER BY a; a 1 2 TRUNCATE TABLE t1; SELECT AUTO_INCREMENT FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 't1'; AUTO_INCREMENT 1 INSERT INTO t1 VALUES (NULL), (NULL); SELECT * FROM t1 ORDER BY a; a 1 2 DROP TABLE t1;
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