SQLServer行转列实现思路记录
编程学习 2021-07-05 13:42www.dzhlxh.cn编程入门
SQLServer行转列的sql语句有很多，可以使用静态的、动态的、Case When等等，均能实现
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
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
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
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
相关的数据表：
1.Score表
2.[User]表
SQL语句如下：
--方法一：静态SQL
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
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
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