删除MySql之前触发 [英] Trigger before delete MySql

问题描述

我有一个名为user的表.该表具有部门表的外键.一个用户可以与一个部门关联.在删除部门之前，我想将任何具有该部门ID的用户设置为默认值(1)，以避免参照完整性错误.

I have a table named user. This table has a foreign key to a department table. One user can be associated with one department. Before deleting a department, I would like to set any user (having that department ID) to a default value (1) to avoid a referential integrity error.

您知道一个很好的例子吗?大多数示例表明触发器已应用于一张表.这里的触发器应该在部门上触发，但要更改用户表中的值.

Do you know a good example. Most examples shows that the trigger is applied to one table. Here the trigger should be triggered on department but change values in user table.

谢谢.

推荐答案

我尚未对其进行测试，但是

I haven't tested it, but based on the documentation, this looks about right:

CREATE TRIGGER update_user_before_delete BEFORE DELETE ON department
  FOR EACH ROW BEGIN
    UPDATE user SET department = 1 WHERE department = OLD.department;
  END;

这篇关于删除MySql之前触发的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！