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