OS: centos 6.3
DB：5.5.14
mysql> select database();
+------------+
| database() |
+------------+
| sakila |
+------------+
1 row in set (0.00 sec)
mysql> delete from actor;
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (`sakila`.`film_actor`, CONSTRAINT `fk_film_actor_actor` FOREIGN KEY (`actor_id`) REFERENCES `actor` (`actor_id`) ON UPDATE CASCADE)
mysql> truncate table actor;
ERROR 1701 (42000): Cannot truncate a table referenced in a foreign key constraint (`sakila`.`film_actor`, CONSTRAINT `fk_film_actor_actor` FOREIGN KEY (`actor_id`) REFERENCES `sakila`.`actor` (`actor_id`))
mysql> show index from actor;
+-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| actor | 0 | PRIMARY | 1 | actor_id | A | 200 | NULL | NULL | | BTREE | | |
| actor | 1 | idx_actor_last_name | 1 | last_name | A | 200 | NULL | NULL | | BTREE | | |
+-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
mysql> set foreign_key_checks=0;
Query OK, 0 rows affected (0.00 sec)
mysql> delete from actor;
Query OK, 200 rows affected (0.01 sec)
mysql> set foreign_key_checks=1;
Query OK, 0 rows affected (0.00 sec)
DB：5.5.14
mysql> select database();
+------------+
| database() |
+------------+
| sakila |
+------------+
1 row in set (0.00 sec)
mysql> delete from actor;
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (`sakila`.`film_actor`, CONSTRAINT `fk_film_actor_actor` FOREIGN KEY (`actor_id`) REFERENCES `actor` (`actor_id`) ON UPDATE CASCADE)
mysql> truncate table actor;
ERROR 1701 (42000): Cannot truncate a table referenced in a foreign key constraint (`sakila`.`film_actor`, CONSTRAINT `fk_film_actor_actor` FOREIGN KEY (`actor_id`) REFERENCES `sakila`.`actor` (`actor_id`))
mysql> show index from actor;
+-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| actor | 0 | PRIMARY | 1 | actor_id | A | 200 | NULL | NULL | | BTREE | | |
| actor | 1 | idx_actor_last_name | 1 | last_name | A | 200 | NULL | NULL | | BTREE | | |
+-------+------------+---------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
mysql> set foreign_key_checks=0;
Query OK, 0 rows affected (0.00 sec)
mysql> delete from actor;
Query OK, 200 rows affected (0.01 sec)
mysql> set foreign_key_checks=1;
Query OK, 0 rows affected (0.00 sec)
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/28939273/viewspace-1249694/ ，如需转载，请注明出处，否则将追究法律责任。
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