mysql - 收到 "[Err] 1111 - Invalid use of group function"错误

Question

我目前正在执行此查询:

SELECT Date_Format(M.Signupdate,"%Y-%m") as YearMonth,
SUM(IF(Count(H.Nr) >= 0,1,0)) ,
SUM(IF(Count(H.Nr) >= 1,1,0)) ,
SUM(IF(Count(H.Nr) >= 2,1,0)) ,
SUM(IF(Count(H.Nr) >= 3,1,0)) 
FROM people M 
INNER JOIN History H ON H.login = M.Login 
WHERE
M.Masteraccount = "" AND
M.logincount > 5 AND
DATEDIFF(M.lastlogin,M.Signupdate) >= 3 AND
DATEDIFF(H.EntryDate,M.Signupdate) <= 151
GROUP BY YearMonth ORDER BY YearMonth ;

但是，我不断收到“[Err] 1111 - 组功能使用无效”错误。如果我删除 SUM，它就工作得很好。请问有人可以回答我吗？

Answer 1

您不能在GROUP BY 中使用别名。您需要将 Date_Format(M.Signupdate,"%Y-%m") 放入 GROUP BY 中才能使其正常工作。此外，您不能嵌套聚合函数，因此您需要使用子查询来获取 count，然后使用 sum:

select YearMonth,
    SUM(IF(CountNR >= 0,1,0)) ,
    SUM(IF(CountNR >= 1,1,0)) ,
    SUM(IF(CountNR >= 2,1,0)) ,
    SUM(IF(CountNR >= 3,1,0)) 
from
(
    SELECT Date_Format(M.Signupdate,"%Y-%m") as YearMonth,
        Count(H.Nr) CountNR 
    FROM people M 
    INNER JOIN History H 
      ON H.login = M.Login 
    WHERE M.Masteraccount = "" AND
      M.logincount > 5 AND
      DATEDIFF(M.lastlogin,M.Signupdate) >= 3 AND
      DATEDIFF(H.EntryDate,M.Signupdate) <= 151
    GROUP BY Date_Format(M.Signupdate,"%Y-%m") 
) src
GROUP BY YearMonth
ORDER BY YearMonth;