在mySql中创建外键时出现问题 | 在mySql中创建外键时出现问题

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问题描述

  ALTER TABLE`users`添加外键（ `id`）
 REFERENCES`user_login`（`user_id`）
 ON DELETE CASCADE;

创建成功后，我执行一条删除语句

  DELETE从user_login WHERE user_id = 1576;

然而在用户行中仍然存在引用它的行。我打开了mysql工作台，并没有显示任何外键创建的迹象。有谁知道这是为什么？或者我做错了什么？这是两个表中的一对一的关系。

解决方案

表格可能是MyISAM格式，支持外键。

尝试将其转换为InnoDB：

 改变表用户引擎= InnoDB;

I created a foreign key in my sql by the following statemnt..

ALTER TABLE `users` ADD FOREIGN KEY ( `id`)
REFERENCES `user_login` (`user_id`)
ON DELETE CASCADE ;

The creation appears to succeed then after that I execute a delete statement

DELETE From user_login WHERE user_id = 1576;

yet in users the row still exists that is referencing that. I open up the mysql workbench and it doesn't show any signs that the foreign key was created. Does anyone know why this would be? Or what I am doing wrong? It is a one-to-one relationship in the two tables.

解决方案

The table may be in MyISAM format, which does not support foreign keys.

Try converting it to InnoDB first:

alter table users engine=InnoDB;

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