在MySQL中删除计数大于1的重复行

Question

需要有关MySQL查询的帮助，以删除userID计数大于1且acl值= 4的行。

我尝试作为选择查询的内容：

DELETE FROM `users_acl` 
WHERE userID IN(
    SELECT * FROM `users_acl` 
    WHERE `acl` BETWEEN 2 AND 4 
    GROUP BY userID 
    HAVING COUNT(userID) > 1
);

但是找不到在同一查询中删除行的正确方法。

表结构

+--------+-----+---------+
| userID | acl | deleted |
+--------+-----+---------+
|     27 |   2 |       0 |
|     28 |   2 |       0 |
|     31 |   2 |       0 |
|     42 |   2 |       0 |
|     42 |   4 |       0 |
|     45 |   1 |       0 |
|     51 |   1 |       0 |
|     54 |   1 |       0 |
|     63 |   2 |       0 |
|     63 |   4 |       0 |
|     64 |   1 |       0 |
|     69 |   2 |       0 |
|     73 |   2 |       0 |
|     73 |   4 |       0 |
|     76 |   1 |       0 |
|     77 |   2 |       0 |
|     77 |   4 |       0 |
+--------+-----+---------+

Answer 1

在MySQL中，您无法同时从要删除的表中进行选择。但是使用临时表可以克服这个问题

DELETE FROM `users_acl` 
WHERE userID IN
(
    SELECT * FROM
    (
       SELECT userID
       FROM `users_acl`
       GROUP BY userID 
       HAVING COUNT(userID) > 1
       AND SUM(`acl` = 4) > 0
   ) tmp
);

或join改用

DELETE u
FROM `users_acl` u
JOIN 
(
    SELECT userID
    FROM `users_acl`
    GROUP BY userID 
    HAVING COUNT(userID) > 1
    AND SUM(`acl` = 4) > 0
) tmp on tmp.userID = u.userID