MySQL DELETE 使用 Have 和 Count 的子查询

Posted 2023-02-24

【中文标题】MySQL DELETE 使用 Have 和 Count 的子查询

【英文标题】：MySQL DELETE With a Sub-Query using Having and Count

【发布时间】：2011-06-23 15:18:02

【问题描述】：

我正在尝试使用以下查询删除多个条目：

首先，我使用此查询找到要删除的条目：

SELECT guid FROM account GROUP BY guid,type HAVING count(type) > 1);

然后我将此查询添加到 DELETE 语句中：

DELETE FROM account WHERE guid IN (SELECT guid FROM account GROUP BY guid,type HAVING count(type) > 1);

但我得到这个错误：

您不能在 FROM 子句中指定目标表 'account' 进行更新

【问题讨论】：

看这里：***.com/questions/45494/…

【参考方案1】：

我认为您需要使用临时表来满足您的需求，如下所示：

第一步：创建临时表

CREATE TEMPORARY TABLE MyTemp
SELECT guid FROM account 
GROUP BY guid,type HAVING count(type) > 1;

在你的删除语句中使用临时表

DELETE FROM account 
WHERE guid IN (SELECT guid FROM MyTemp);

删除临时表

DROP TEMPORARY TABLE MyTemp;

编辑：我认为使用 *两个嵌套表也可以解决：

  DELETE FROM account 
    WHERE guid IN 
     (SELECT guid FROM 
       (SELECT guid FROM account 
       GROUP BY guid,type HAVING count(type) > 1) as MyTemp
    )

【参考方案2】：

你的问题已经解决了，按照下面的操作就行了..

    DELETE FROM account 

      WHERE guid IN 

     (SELECT * FROM 

       (SELECT guid FROM account 

          GROUP BY guid,type 

          HAVING  count(type) > 1) AS a);

【讨论】：

谢谢 Abhik，但您不能从您选择的同一个表中删除。

【参考方案3】：

首先创建视图

create view view_acct as 
SELECT guid FROM account 
GROUP BY guid,type HAVING count(type) > 1;

使用后查看

DELETE FROM account WHERE guid in (select * from view_acct);