Question

我有两张桌子，第一张看起来像这样

Leave       Limit
-----------------
vacation      15
sick          10
absent         9

和第二个..

Person             Leave      Use
-------------------------------
Chuck Norris     sick        1
Bruce Lee        absent      2

我想要它做的是加入表格，当我选择一个人时，它将显示如下

ex. i select Chuck Norris 

Leave        Limit        Use
------------------------------
vacation       15          0
sick           10          1
absent          9          0

这就是我已经完成的事情......

SELECT        LeavetypTbl.Leave, LeavetypTbl.Limit, ISNULL(SUM(LeaveTbl.Use), 0) AS Expr1, 
              LeavetypTbl.Limit- ISNULL(SUM(LeaveTbl.USE), 0) AS DayLeft
FROM          LeavetypTbl LEFT OUTER JOIN
              LeaveTbl ON LeavetypTbl.Leave = LeaveTbl.Leave
WHERE         LeaveTbl.Person ='Chuck Norris'
GROUP BY LeavetypTbl.Leave, LeavetypTbl.Limit

但结果并不是我所期待的......很多

Leave    Limit    Use    DayLeft

Sick       10       1          9

我只会获得1行..

Answer 1

您只获得一行，因为您将结果限制为顶级'Chuck Norris'子句中的WHERE。但是，Chuck Norris从未休假或缺席，因此外部联接中的其他两行被WHERE子句消除。将其移至ON子句以获得您期望的结果：

SELECT        LeavetypTbl.Leave, LeavetypTbl.Limit, ISNULL(SUM(LeaveTbl.Use), 0) AS Expr1, 
              LeavetypTbl.Limit- ISNULL(SUM(LeaveTbl.USE), 0) AS DayLeft
FROM          LeavetypTbl LEFT OUTER JOIN
              LeaveTbl ON LeavetypTbl.Leave = LeaveTbl.Leave AND LeaveTbl.Person ='Chuck Norris'
GROUP BY LeavetypTbl.Leave, LeavetypTbl.Limit

Answer 2

在JOIN条件中添加人物过滤器，如下所示：

SELECT        LeavetypTbl.Leave, LeavetypTbl.Limit, ISNULL(SUM(LeaveTbl.Use), 0) AS Expr1, 
              LeavetypTbl.Limit- ISNULL(SUM(LeaveTbl.USE), 0) AS DayLeft
FROM          LeavetypTbl LEFT OUTER JOIN
              LeaveTbl ON LeavetypTbl.Leave = LeaveTbl.Leave
                          and LeaveTbl.Person ='Chuck Norris'
GROUP BY LeavetypTbl.Leave, LeavetypTbl.Limit

我无法正确查询此查询

2 个答案: