数据库 行列相互转化

--行列互转

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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

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--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)

**/

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