最近面试遇到了一道面试题,顿时有点迷糊,只说出了思路,后来百度了一下,整理了一下思路,于是记录下来,方便以后学习。(面试题请参见附件)
相关的数据表:
1.Score表
2.[User]表
SQL语句如下:
–方法一:静态SQL
复制代码 代码如下:
SELECT * FROM
(SELECT UID,Name, Score,ScoreName FROM Score,[User] WHERE Score.UID=[User].ID) AS SourceTable
PIVOT(AVG(Score)FOR ScoreName IN ([英语], [数学])) AS a
–方法二:动态SQL
复制代码 代码如下:
DECLARE @s NVARCHAR(4000)
SELECT @s = ISNULL(@s + ‘,’, ”) + QUOTENAME(ScoreName)
FROM (select distinct ScoreName from Score) as A —列名不要重复
Declare @sql NVARCHAR(4000)
SET @sql=’
select r.* from
(select UID,Name,ScoreName,Score from Score,[User] where Score.UID=[User].ID) as t
pivot
(
max(t.Score)
for t.ScoreName in (‘+@s+’)
) as r’
EXEC( @sql)
–方法三:Case When
复制代码 代码如下:
select
row_number() OVER(ORDER BY [User].ID) as 编号,
UID as 用户编号,
Name as 姓名,
max(case ScoreName when ‘英语’ then Score else 0 end) 英语,
max(case ScoreName when ‘数学’ then Score else 0 end) 数学
from Score,[User] WHERE Score.UID=[User].ID
group by UID,[User].ID,Name
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