sqlserver中查询横表变竖表的sql语句简析

sqlserver中查询横表变竖表的sql语句简析

 

 

 

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：

 

 

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：

 

 

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。http://www.smalluv.com/mssql_211.html