删除主键也删除外键。

I have two table, with a PK of ID. If say I delete the entry for ID = 1, I want it to automatically delete the FK of ID in the other table. In other words I want so that it should also delete all entries with ID = 1 in the other table. How can I do this? I have linked the PK-FK relationship, but when I delete the entry with ID 1 in the PK table it doesn't delete the FK.

我有两个表，有一个ID的PK，如果我删除ID = 1的条目，我希望它能自动删除另一个表中的ID FK。换句话说，我希望它也应该删除其他表中ID = 1的所有条目。我该怎么做呢?我已经链接了PK-FK关系，但是当我在PK表中删除ID 1的条目时，它不会删除FK。

2 个解决方案

#1

Make sure you're using the InnoDB engine for both tables, and add a foreign-key constraint specifying on delete cascade. Your table creation SQL should look something like this:

确保您使用的是两个表的InnoDB引擎，并在delete cascade中添加一个外键约束。您的表创建SQL应该是这样的:

create table child_table (
    parent_id int references parent_table(id) on delete cascade
) engine 'innodb';

where child_table and parent_table are the names of your child and parent tables.

其中child_table和parent_table是子表和父表的名称。

#2

You have to define your Foreign Key constraints as ON DELETE CASCADE.

在删除级联时，必须定义外键约束。

Note: You need to use InnoDB storage engine, he default MyISAM storage engine not support foreign keys relation.

注意:您需要使用InnoDB存储引擎，他默认MyISAM存储引擎不支持外键关系。

CREATE TABLE `table2` (
`id` int(11) NOT NULL auto_increment,
`name` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `ids` (`ids`)
CONSTRAINT `foreign` FOREIGN KEY (`ids`)
REFERENCES `table2` (`ids`) ON DELETE CASCADE ON UPDATE CASCADE
)

#1