sum列基于另一列的值，按第三列分组

Question

我迷失在这一个。看似简单，但无法得到答案。我有一种感觉，我可能会对答案感到尴尬。好吧，好吧。我试图在WebMatrix 3.0中这样做，我相信它的SQL Express。不确定。

Table Dlivry

tID    cID    Boxes    Delivered
1      01     5        1
2      03     7        1
3      01     2        0
4      01     3        1
5      03     5        1
6      05     4        1
7      05     10       0

我想要的是

Client Delivered   NotDelivered
01     8           2
03     12          0
05     4           10

到目前为止我做了什么

SELECT D1.cid        AS Client, 
       Sum(D1.boxes) AS Delivered, 
       Sum(D2.boxes) AS NotDelivered 
FROM   dlivr D1, 
       dlivry D2 
WHERE  D1.delivered = 1 
       AND D2.delivered = 0 
       AND D1.cid = D2.cid 
GROUP  BY cid 

好的就是。准备好让我感到尴尬，我准备好学习。

感谢您的帮助。

Answer 1

由于您正在使用内部联接，因此您只会获得包含已发送和未发送框的CID行。所以你不会获得CID = 3的任何行。试试这个：

SELECT CID,
       SUM(CASE WHEN Delivered = 1 THEN boxes ELSE 0 END) AS Delivered,
       SUM(CASE WHEN Delivered = 0 THEN boxes ELSE 0 END) AS NotDelivered
FROM Dlivr
GROUP BY CID