Question

我何时使用以下查询：

SELECT  
    AC.iJobID as JobID,
    ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber,     
    (SELECT COUNT (*) FROM tbUS_ReferJob WHERE iJobId_FK = 202424 AND sReferredFrom = 'F' AND iUserId_FK = 9550) AS FaceBook_Applications
FROM tbUS_AffiliateJobCount AC,tbUS_ReferJob RJ
WHERE AC.iJobID = 202424 AND RJ.iJobId_FK = 202424
GROUP BY AC.iJobID

它给出了正确的结果。

JobID   RowNumber   FaceBook_Applications
202424  1           2

但是当我使用下面的查询时

SELECT
    AC.iJobID as JobID,
    ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber,     
    SUM(CASE WHEN RJ.sReferredFrom = 'F' THEN 1 ELSE 0 END) AS FaceBook_Applications
FROM tbUS_AffiliateJobCount AC,tbUS_ReferJob RJ
WHERE AC.iJobID = 202424 AND RJ.iJobId_FK = 202424
GROUP BY AC.iJobID

提供的结果不正确

JobID   RowNumber   FaceBook_Applications
202424  1           12

现在我的问题是

背后的原因是什么？
如何使用SUM()功能降低成本呢？

任何建议都会有所帮助。

感谢您的时间。

更新

SELECT  AC.iJobID as JobID,
        ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber,     
        SUM(CASE WHEN (RJ.sReferredFrom = 'F' AND RJ.iJobId_FK = 202424 AND RJ.iUserId_FK = 9550) THEN 1 ELSE 0 END) AS FaceBook_Applications
FROM    tbUS_AffiliateJobCount AC,tbUS_ReferJob RJ
WHERE   AC.iJobID = 202424 AND RJ.iJobId_FK = 202424
GROUP BY AC.iJobID

它正在给予：

JobID   RowNumber   FaceBook_Applications
202424  1            8

更新2

SELECT iJobID_FK, sReferredFrom FROM tbUS_ReferJob WHERE iUserID_FK=9550 AND iJobID_FK=202424 AND sReferredFrom='F'

结果：

iJobID_FK   sReferredFrom
202424          F
202424          F

Answer 1

在第一个查询中，您将子查询限制为：

WHERE iUserId_FK = 9550

第二个查询中缺少此限制。它应该是这样的：

SELECT  AC.iJobID as JobID,
        ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber,     
        SUM(CASE WHEN RJ.sReferredFrom = 'F' THEN 1 ELSE 0 END) AS FaceBook_Applications
FROM    tbUS_AffiliateJobCount AC,tbUS_ReferJob RJ
WHERE   AC.iJobID = RJ.iJobId_FK 
AND     AC.iJobID = 202424 
AND     RJ.iUserId_FK = 9550

Answer 2

如果我正确查看，我认为您在第二个查询中缺少过滤器

AND iUserId_FK = 9550

第二个查询应如下所示：

SELECT
    AC.iJobID as JobID,
    ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber,     
    SUM(CASE WHEN RJ.sReferredFrom = 'F'  AND iUserId_FK = 9550 THEN 1 ELSE 0 END) AS FaceBook_Applications
FROM tbUS_AffiliateJobCount AC,tbUS_ReferJob RJ
WHERE AC.iJobID = 202424 AND RJ.iJobId_FK = 202424
GROUP BY AC.iJobID

修改

我认为连接条件可能存在一些问题...尝试在求和之前进行更清晰的连接

SELECT AC.iJobID as JobID, ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber, SUM(CASE WHEN RJ.sReferredFrom = 'F' THEN 1 ELSE 0 END) AS FaceBook_Applications FROM tbUS_AffiliateJobCount AC JOIN tbUS_ReferJob RJ ON AC.iJobID = RJ.iJobId_FK AND Rj.iUserId_FK = 9550 WHERE AC.iJobID = 202424 GROUP BY AC.iJobID

编辑2

SELECT AC.iJobID as JobID, ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber, COUNT(*) AS FaceBook_Applications FROM tbUS_AffiliateJobCount AC JOIN tbUS_ReferJob RJ ON AC.iJobID = RJ.iJobId_FK AND Rj.iUserId_FK = 9550 AND RJ.sReferredFrom = 'F' WHERE AC.iJobID = 202424 GROUP BY AC.iJobID

Answer 3

进行第二次查询（我将在此重复）：

SELECT
    AC.iJobID as JobID,
    ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber,     
    SUM(CASE WHEN RJ.sReferredFrom = 'F' THEN 1 ELSE 0 END) AS FaceBook_Applications
FROM tbUS_AffiliateJobCount AC,tbUS_ReferJob RJ
WHERE AC.iJobID = 202424 AND RJ.iJobId_FK = 202424
GROUP BY AC.iJobID

并删除（或注释掉）所有分组＆amp;聚合（排名也是如此，因为它对我的建议毫无用处），例如：

SELECT
    AC.iJobID as JobID, RJ.iUserId_FK,
    ROW_NUMBER()OVER (ORDER BY AC.iJobID) AS RowNumber,
    SUM(CASE WHEN RJ.sReferredFrom = 'F' THEN 1 ELSE 0 END) AS FaceBook_Applications
FROM tbUS_AffiliateJobCount AC,tbUS_ReferJob RJ
WHERE AC.iJobID = 202424 AND RJ.iJobId_FK = 202424
GROUP BY AC.iJobID

现在运行生成的查询，看看它产生了多少F个。我的观点是，连接的结果很可能包含许多重复项，因为两个表的子集都返回多行并且导致旧的Cartesian product。解决方案可能包括清理原始表中的重复项（如果适用），或者使WHERE条件更具体。

SQL Server中的聚合函数相关问题

3 个答案: