MYSQL删除count（*）= 1的所有结果 [英] MYSQL delete all results having count(*)=1

问题描述

我有一个关于sesskey（varchar32，index）和products（int11）两个字段的表，现在我必须删除具有sesskey count（*）= 1的所有行。
我正在尝试

例子：

 从...中删除（sesskey）（sesskey从sesskey中选择计数（*）= 1）的位置（
  

sesskey字段不能作为主键，因为它的重复。

解决方案

  DELETE si 
 FROM t_session si 
 JOIN（
 SELECT sesskey 
 FROM t_session so 
 GROUP BY 
 sesskey 
 HAVING COUNT（*）= 1 
 ）q 
 ON q.sesskey = si.sesskey 
  

您需要在此加入。使用相关子查询将无法正常工作。

请参阅我的博客中的以下文章以获取更多详细信息：

• 保留行

I have a table taged with two fields sesskey (varchar32 , index) and products (int11), now I have to delete all rows that having group by sesskey count(*) = 1. I'm trying a fews methods but all fails.

Example:

delete from taged where sesskey in (select sesskey from taged group by sesskey having count(*) = 1)

The sesskey field could not be a primary key because its repeated.

解决方案

DELETE  si
FROM    t_session si
JOIN    (
        SELECT  sesskey
        FROM    t_session so
        GROUP BY
                sesskey
        HAVING  COUNT(*) = 1
        ) q
ON      q.sesskey = si.sesskey

You need to have a join here. Using a correlated subquery won't work.

See this article in my blog for more detail:

• Keeping rows

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