mysql - MySQL从数据库不在的地方选择

我需要清理一个数据库中的记录，如果它们不存在于其他数据库中。
很难解释，下面是一个例子：

Table Users
-----------
id
username
password

Table Articles
--------------
id
title
created_by
edited_by

created_by和deleted_by包含用户ID。
我有3-4个表，其结构与articles表几乎相同，我想从没有任何记录的表用户（如tables）中删除用户。
我的意思是在created_by和edited_by表中的任何一篇文章中都找不到ID的用户。
怎么做？
我首先想看看是否可以根据用户选择所有表的所有数据，但是服务器无法执行查询：

SELECT * FROM `users`
JOIN `articles`
ON `articles`.`created_by` = `users`.`id`
AND `articles`.`edited_by` = `users`.`id`
JOIN `articles_two`
ON `articles_two`.`created_by` = `users`.`id`
AND `articles_two`.`edited_by` = `users`.`id`
JOIN `articles_three`
ON `articles_three`.`created_by` = `users`.`id`
AND `articles_three`.`edited_by` = `users`.`id`
JOIN `articles_four`
ON `articles_four`.`created_by` = `users`.`id`
AND `articles_four`.`edited_by` = `users`.`id`
JOIN `articles_five`
ON `articles_five`.`created_by` = `users`.`id`
AND `articles_five`.`edited_by` = `users`.`id`
JOIN `articles_six`
ON `articles_six`.`created_by` = `users`.`id`
AND `articles_six`.`edited_by` = `users`.`id`;

最佳答案

我认为最干净的方法是not in子句中的select：

select *
from users u
where u.id not in (select created_by from articles where created_by is not null) and
      u.id not in (select edited_by from articles where edited_by is not null) and
      u.id not in (select created_by from articles_two where created_by is not null) and
      u.id not in (select edited_by from articles_two where edited_by is not null) and
      u.id not in (select created_by from articles_three where created_by is not null) and
      u.id not in (select edited_by from articles_three where edited_by is not null) and
      u.id not in (select created_by from articles_four where created_by is not null) and
      u.id not in (select edited_by from articles_four where edited_by is not null)

应该通过在不同的created_by和edited_by列上设置索引来提高性能。