分组依据语法错误

Question

这显示为 NULL。

SELECT Gender, SUM( DISTINCT Freq ) AS TotalApp, 
(
    SELECT SUM( Freq ) 
    FROM ucbadmissions
    WHERE Admit = 'Rejected'
    IN (
        SELECT Admit
        FROM ucbadmissions
       )
) AS AdmRate
FROM ucbadmissions
GROUP BY Gender

这显示为错误。

SELECT Gender, SUM( DISTINCT Freq ) AS TotalApp, 
(
    SELECT  SUM( Freq ) 
    FROM ucbadmissions
    WHERE Admit != 'Rejected'
    Group By Gender
) AS AdmRate
FROM ucbadmissions
Group By Gender

表格示例。

承认性别部门频率
录取男 A 512
拒绝男 A 313
录取女 A 89
拒绝女 A 19
拒绝女 B 8
录取女 B 17
拒绝男 B 207
录取男 B 353

Answer 1

SELECT      Gender, SUM(Freq) AS TotalApp,
            SUM(CASE WHEN Admit = 'Admitted' THEN Freq ELSE 0 END) / SUM(Freq) AS AdmitRate
FROM        ucbAdmissions
GROUP BY    Gender

Answer 2

如果我正确理解您的要求，这应该可以解决问题：

SELECT 
  Gender, 
  SUM(Freq) AS TotalApp,
  SUM(CASE WHEN Admit = 'Rejected' THEN 0 else Freq END) AS AdmRate
FROM ucbadmissions
GROUP BY Gender

这将返回性别加上申请总数加上每个性别的成功申请数。