在 MySQL 中使用 Join 删除

2021-11-20 00:00:00 mysql

这是创建我的表的脚本:

Here is the script to create my tables: 

CREATE TABLE clients (
   client_i INT(11),
   PRIMARY KEY (client_id)
);
CREATE TABLE projects (
   project_id INT(11) UNSIGNED,
   client_id INT(11) UNSIGNED,
   PRIMARY KEY (project_id)
);
CREATE TABLE posts (
   post_id INT(11) UNSIGNED,
   project_id INT(11) UNSIGNED,
   PRIMARY KEY (post_id)
);

在我的 PHP 代码中，删除客户端时，我想删除所有项目帖子:

In my PHP code, when deleting a client, I want to delete all projects posts:

DELETE 
FROM posts
INNER JOIN projects ON projects.project_id = posts.project_id
WHERE projects.client_id = :client_id;

posts 表没有外键 client_id，只有 project_id.我想删除项目中传递了 client_id 的帖子.

The posts table does not have a foreign key client_id, only project_id. I want to delete the posts in projects that have the passed client_id.

这现在不起作用，因为没有帖子被删除.

This is not working right now because no posts are deleted.

推荐答案

您只需要指定要从 posts 表中删除条目:

You just need to specify that you want to delete the entries from the posts table:

DELETE posts
FROM posts
INNER JOIN projects ON projects.project_id = posts.project_id
WHERE projects.client_id = :client_id

有关更多信息，您可以查看此替代答案

For more information you can see this alternative answer

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