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sqlserver中查询横表变竖表的sql语句简析

　　本文标签：横表,竖表

首先是三张表， CNo对应的是课程，在这里我就粘贴了 。            

                              主表

                 人名表

按照常规查询

SELECT s.SName, c.CName,s2.SCgrade

  FROM S s INNER JOIN SC s2 ON s2.SNo = s.SNo INNER JOIN C c ON c.CNo = s2.CNo

那么结果是这样的

 

但是这是横表 不是我想看到的结果 。

我们要看到这样的结果：

那么怎么办呢？
第一种写法：

复制代码 代码如下:

SELECT w.SName,
sum(case when w.CNo= 1 then w.SCgrade ELSE 0 END) AS 语文,
sum(case WHEN w.CNo =2 THEN w.SCgrade ELSE 0 END) AS 数学,
sum(case when w.CNo= 3 then w.SCgrade ELSE 0 END) AS 英语
FROM
(SELECT s.SNo,s.SName, s2.CNo, s2.SCgrade FROM s s INNER JOIN SC s2 ON s2.SNo = s.SNo WHERE s.SNo IN (SELECT c.SNo FROM sc c GROUP BY c.SNo ))
AS w GROUP BY w.SName
第二种写法：
复制代码 代码如下:

SELECT s.SName,
sum(case when s2.CNo= 1 then s2.SCgrade ELSE 0 END) AS 语文,
sum(case WHEN s2.CNo =2 THEN s2.SCgrade ELSE 0 END) AS 数学,
sum(case when s2.CNo= 3 then s2.SCgrade ELSE 0 END) AS 英语
FROM
S s INNER JOIN SC s2 ON s2.SNo = s.SNo
INNER JOIN C c ON c.CNo = s2.CNo
GROUP BY s.SNo,
s.SName

这是我工作遇到过得情况，总结下来 。如果有遇到这种情况的话可以参考下 。