MySQL ERROR 1451 (23000) 外键异常处理

 

 

1、执行delete报错

mysql> delete from JBPM4_EXECUTION;

ERROR 1451 (23000): Cannot delete or updatea parent row: a foreign key constraint fails (`jbpm_db`.`JBPM4_EXECUTION`,CONSTRAINT `FK_EXEC_INSTANCE` FOREIGN KEY (`INSTANCE_`) REFERENCES`JBPM4_EXECUTION` (`DBID_`))

mysql>

 

 

表有外键所以delete报错了，这里有2种办法处理：

（1）      临时设置外键失效

（2）      删除表涉及到的外键的表的数据

 

 

 

2、外键失效的处理方案

mysql> SET FOREIGN_KEY_CHECKS = 0;  # 临时设置外键失效 Query OK, 0 rows affected (0.00 sec)   mysql> mysql> delete from JBPM4_EXECUTION;  #执行删除操作 Query OK, 110 rows affected (0.00 sec)   mysql> mysql> SET FOREIGN_KEY_CHECKS = 1;  # 操作结束后恢复外键                                                                                                                                                                                            Query OK, 0 rows affected (0.00 sec)   mysql>

 

 

3、删除外键表的数据的出来方案

 

先查询表锁涉及到的所有外键情况，查询sql如下：

SELECT TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME                                                                   FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE REFERENCED_TABLE_NAME = 'JBPM4_EXECUTION';

 

执行查询会看到有如下外键：

E:\u\mysql\problem\pic\02.jpg

 

 

然后看到涉及到外键的表的有 JBPM4_VARIABLE、JBPM4_EXECUTION、JBPM4_SWIMLANE三张表，接下来清除这三张表的数据即可。

 

mysql> delete from JBPM4_VARIABLE; Query OK, 1404 rows affected (0.03 sec)   mysql> delete fromJBPM4_SWIMLANE; Query OK, 13 rows affected (0.03 sec)   mysql>  delete from JBPM4_EXECUTION;  # 这里报错是因为表自己给自己设置了外键关联，所以清除外键字段的数据，就可以了 ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (`jbpm_db`.`JBPM4_EXECUTION`, CONSTRAINT `FK_EXEC_INSTANCE` FOREIGN KEY (`INSTANCE_`) REFERENCES `JBPM4_EXECUTION` (`DBID_`)) mysql> mysql> update JBPM4_EXECUTION set INSTANCE_=null,PARENT_=null,SUBPROCINST_=null,SUPEREXEC_=null; Query OK, 203 rows affected (0.02 sec) Rows matched: 203  Changed: 203  Warnings: 0   mysql>  delete from JBPM4_EXECUTION;  # 所有外键关联数据都清除了，现在删除数据可以了。 Query OK, 203 rows affected (0.02 sec)   mysql>