ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails

Mysql出现问题:ERROR 1451 (23000): Cannot delete or updatea parent row: a foreign key constraint fail解决方案 Mysql出现问题:ERROR 1451 (23000): Cannot delete or updatea parent row: a foreign key constraint fails解决方案 阅读详情

在数据库nova的instances表中删除虚机时失败:

delete from instances where vm_state='deleted';

报错:
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (nova.block_device_mapping, CONSTRAINT block_device_mapping_instance_uuid_fkey FOREIGN KEY (instance_uuid) REFERENCES instances (uuid))

解决办法:

SET foreign_key_checks = 0;  // 先设置外键约束检查关闭
 
delete from instances where vm_state='deleted'; //删除状态为deleted的虚机
 
SET foreign_key_checks = 1; // 开启外键约束检查,以保持表结构完整性

删除成功:

MariaDB [nova]> delete from instances where vm_state='deleted';

Query OK, 94 rows affected (0.02 sec)

【异常】删除MySQL数据后提示Cannot delete or update a parent row: a foreign key constraint fails 在数据库操作中,出现“Error synchronizing data with database”错误,通常是由于外键约束导致的。具体表现为无法删除或更新父表中的数据,因为子表中存在相关的外键约束。解决此问题的方法包括:首先删除子表中的关联数据,然后再删除父表中的记录;或者通过修改外键约束,添加ON DELETE CASCADE选项,实现级联删除;此外,还可以暂时禁用外键约束,但这种方法存在数据不一致的风险,不建议频繁使用。为预防此类问题,建议在设计数据库时,对于需要级联删除的场景,直接设置好ON DEL 阅读详情

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