sql - 使用 GROUP BY 删除

Question

如何更改此 SELECT 使其成为用于删除的标准？

SELECT COUNT(empid), empid, status, deptid from tableA 
GROUP BY empid, status, deptid HAVING status is null and deptid = 5

Answer 1

你想删除什么？

如果只是在 deptId 5 中记录具有 NULL 状态的记录，则使用

WHERE status is NULL and DeptID = 5

不是很清楚，如果你正在寻找更多...

Answer 2

我猜，用 GROUP BY 删除可能不起作用。

您可以尝试以下方法，看看它是否有效。

DELETE 
FROM tableA
WHERE status is null AND deptid=5

Answer 3

DELETE FROM tableA 
WHERE status is null AND deptid = 5 

Answer 4

Delete from tableA a, 
(SELECT COUNT(empid) as count, empid, status, deptid from tableA 
    GROUP BY empid, status, deptid HAVING status is null and deptid = 5) as b 
where a.empid = b.empid
and a.status = b.status
and a.deptid = b.deptid
and b.count > 5

像这样的东西会是你正在寻找的吗？它将删除属于计数> 5的组的所有记录

否则，您实际上并没有从 group by 中删除值，并且可以使用简单的 delete；

Delete from tableA 
where status is null 
and deptid = 5