mysql - 如果 B 中存在，则从 A 中删除

Question

我有两张桌子：

• USER
• MAILING

MAILING表有一列email。

USER表有users很多email。

现在我想删除这样的东西：

DELETE email FROM mailing WHERE users.email = mailings.email 

因此，如果此电子邮件存在于用户表中，我需要从表邮件中删除电子邮件。

Answer 1

你可以用这个

DELETE FROM mailing WHERE email IN (SELECT email FROM users)

或者这个使用JOIN

DELETE M
FROM mailing M
  JOIN users U
    ON M.email = U.email 

Answer 2

如果要更新列，请update不要尝试delete

UPDATE mailing 
inner join users on users.email = mailings.email  
set email=null 

或者你想删除记录试试这个：

DELETE m 
FROM mailing m 
inner join users u on u.email=m.email

Answer 3

您可以使用EXISTSMySQL 的子句如下 -

delete from mailing where exists(select * from user where user.email=mailing.email);

无需使用 JOIN

Answer 4

考虑到您想从邮件表中删除所有行，而邮件表中只有一列。

Delete
from mailing where mailing.email 
exists (select email from users where users.email = mailing.email);