SQL行列互转

--行列互转
/******************************************************************************************************************************************************
以学生成绩为例子，比较形象易懂

整理人：中国风(Roy)

日期:2008.06.06
******************************************************************************************************************************************************/

--1、行互列
--> --> (Roy)生成測試數據

if not object_id('Class') is null
    drop table Class
Go
Create table Class([Student] nvarchar(2),[Course] nvarchar(2),[Score] int)
Insert Class
select N'张三',N'语文',78 union all
select N'张三',N'数学',87 union all
select N'张三',N'英语',82 union all
select N'张三',N'物理',90 union all
select N'李四',N'语文',65 union all
select N'李四',N'数学',77 union all
select N'李四',N'英语',65 union all
select N'李四',N'物理',85
Go
--2000方法:
动态:

declare @s nvarchar(4000)
set @s=''
Select     @s=@s+','+quotename([Course])+'=max(case when [Course]='+quotename([Course],'''')+' then [Score] else 0 end)'
from Class group by[Course]
exec('select [Student]'+@s+' from Class group by [Student]')


生成静态:

select
    [Student],
    [数学]=max(case when [Course]='数学' then [Score] else 0 end),
    [物理]=max(case when [Course]='物理' then [Score] else 0 end),
    [英语]=max(case when [Course]='英语' then [Score] else 0 end),
    [语文]=max(case when [Course]='语文' then [Score] else 0 end)
from
    Class
group by [Student]

GO
动态:

declare @s nvarchar(4000)
Select     @s=isnull(@s+',','')+quotename([Course]) from Class group by[Course]
exec('select * from Class pivot (max([Score]) for [Course] in('+@s+'))b')

生成静态:
select *
from
    Class
pivot
    (max([Score]) for [Course] in([数学],[物理],[英语],[语文]))b

生成格式:
/*
Student 数学          物理          英语          语文
------- ----------- ----------- ----------- -----------
李四      77          85          65          65
张三      87          90          82          78

(2 行受影响)
*/

------------------------------------------------------------------------------------------
go
--加上总成绩(学科平均分)

--2000方法:
动态:

declare @s nvarchar(4000)
set @s=''
Select     @s=@s+','+quotename([Course])+'=max(case when [Course]='+quotename([Course],'''')+' then [Score] else 0 end)'
from Class group by[Course]
exec('select [Student]'+@s+',[总成绩]=sum([Score])  from Class group by [Student]')--加多一列(学科平均分用avg([Score]))

生成动态:

select
    [Student],
    [数学]=max(case when [Course]='数学' then [Score] else 0 end),
    [物理]=max(case when [Course]='物理' then [Score] else 0 end),
    [英语]=max(case when [Course]='英语' then [Score] else 0 end),
    [语文]=max(case when [Course]='语文' then [Score] else 0 end),
    [总成绩]=sum([Score]) --加多一列(学科平均分用avg([Score]))
from
    Class
group by [Student]

go

--2005方法:

动态:

declare @s nvarchar(4000)
Select     @s=isnull(@s+',','')+quotename([Course]) from Class group by[Course] --isnull(@s+',','') 去掉字符串@s中第一个逗号
exec('select [Student],'+@s+',[总成绩] from (select *,[总成绩]=sum([Score])over(partition by [Student]) from Class) a
pivot (max([Score]) for [Course] in('+@s+'))b ')

生成静态:

select
    [Student],[数学],[物理],[英语],[语文],[总成绩]
from
    (select *,[总成绩]=sum([Score])over(partition by [Student]) from Class) a --平均分时用avg([Score])
pivot
    (max([Score]) for [Course] in([数学],[物理],[英语],[语文]))b

生成格式:

/*
Student 数学          物理          英语          语文          总成绩
------- ----------- ----------- ----------- ----------- -----------
李四      77          85          65          65          292
张三      87          90          82          78          337

(2 行受影响)
*/

go

--2、列转行
--> --> (Roy)生成測試數據

if not object_id('Class') is null
    drop table Class
Go
Create table Class([Student] nvarchar(2),[数学] int,[物理] int,[英语] int,[语文] int)
Insert Class
select N'李四',77,85,65,65 union all
select N'张三',87,90,82,78
Go

--2000:

动态:

declare @s nvarchar(4000)
select @s=isnull(@s+' union all ','')+'select [Student],[Course]='+quotename(Name,'''')--isnull(@s+' union all ','') 去掉字符串@s中第一个union all
+',[Score]='+quotename(Name)+' from Class'
from syscolumns where ID=object_id('Class') and Name not in('Student')--排除不转换的列
order by Colid
exec('select * from ('+@s+')t order by [Student],[Course]')--增加一个排序

生成静态:
select *
from (select [Student],[Course]='数学',[Score]=[数学] from Class union all
select [Student],[Course]='物理',[Score]=[物理] from Class union all
select [Student],[Course]='英语',[Score]=[英语] from Class union all
select [Student],[Course]='语文',[Score]=[语文] from Class)t
order by [Student],[Course]

go
--2005:

动态:

declare @s nvarchar(4000)
select @s=isnull(@s+',','')+quotename(Name)
from syscolumns where ID=object_id('Class') and Name not in('Student')
order by Colid
exec('select Student,[Course],[Score] from Class unpivot ([Score] for [Course] in('+@s+'))b')

go
select
    Student,[Course],[Score]
from
    Class
unpivot
    ([Score] for [Course] in([数学],[物理],[英语],[语文]))b

生成格式:
/*
Student Course Score
------- ------- -----------
李四      数学      77
李四      物理      85
李四      英语      65
李四      语文      65
张三      数学      87
张三      物理      90
张三      英语      82
张三      语文      78

(8 行受影响)
*/