如何修复我的MySQL错误1093

Question

如何解决此错误

[Err] 1093 - You can't specify target table 'user_log' for update in FROM clause

DELETE 
  user_log
FROM
  user_log
WHERE
  UpdateDate < (SELECT MAX(UpdateDate) 
    FROM user_log 
    AS lookup 
    WHERE Email = user_log.Email)

让我知道

Answer 1

如果要删除表的数据，请使用：

来自[table]的

delete [condition]。

同样适用于max，您必须先对数据进行分组。

DELETE 
FROM
  user_log
WHERE
  UpdateDate < (SELECT MAX(UpdateDate) 
    FROM user_log 
    GROUP BY Email
    HAVING Email = user_log.Email)

当你想在一个组上使用条件时，你必须使用而不是在哪里。

Answer 2

改为;

DELETE 
FROM
  user_log
WHERE
  UpdateDate < (SELECT MAX(UpdateDate) 
FROM user_log 
GROUP BY Email
HAVING Email = user_log.Email)

您无法指定在DELETE语句中删除哪些字段，它们都是。

Answer 3

我不是100％确定你想要做什么，但你可能正在努力做到这一点

DELETE FROM  user_log
WHERE  UpdateDate < (
    SELECT MAX(UpdateDate)     
    FROM user_log AS lookup     
    WHERE Email = lookup.Email
)

希望这适合你。