这段时间一直在找关于交叉表查询的精髓，如下列子
declare @i int,@s nvarchar(1000)
select top 1 @i=count(*),@s='' from #tb group by [姓名] order by count(*) desc
while @i>0
select @s=','+quotename(N'考勤时间'+rtrim(@i))+'=max(case when row='+rtrim(@i)+N' then [考勤时间] else '''' end)'+@s,@i=@i-1
exec(N'select [姓名]'+@s+N'from (Select *,(select count(1) from #tb where [姓名]=a.[姓名] and [考勤时间]<=a.[考勤时间]) as row from #tb a) t group by [姓名]')以前我把能将行转列的精髓归结于函数， 但现在发现跟函数没有关系， 那么SQL 语句是如何实现行转列的呢， 他的精髓是什么，请高人指教，拜谢．
declare @i int,@s nvarchar(1000)
select top 1 @i=count(*),@s='' from #tb group by [姓名] order by count(*) desc
while @i>0
select @s=','+quotename(N'考勤时间'+rtrim(@i))+'=max(case when row='+rtrim(@i)+N' then [考勤时间] else '''' end)'+@s,@i=@i-1
exec(N'select [姓名]'+@s+N'from (Select *,(select count(1) from #tb where [姓名]=a.[姓名] and [考勤时间]<=a.[考勤时间]) as row from #tb a) t group by [姓名]')以前我把能将行转列的精髓归结于函数， 但现在发现跟函数没有关系， 那么SQL 语句是如何实现行转列的呢， 他的精髓是什么，请高人指教，拜谢．
/******************************************************************************************************************************************************
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)
*/
-------------
最近我也学这样.但这动态方法还是没能理解
Set Nocount On
if not object_id('Tempdb..#') is null
drop table #
Go
Create table #([name] nvarchar(2),[namevalue] nvarchar(2))
Insert #
select N'a1',N'00' union all
select N'aa',N'01' union all
select N'ab',N'02'
GoDeclare @Sql nvarchar(Max)
Set @Sql='Select * From # Pivot(Max(namevalue) For name In(' +
Stuff((Select Distinct ','+Quotename(name) From # For Xml Path('')),1,1,'')+
N')) b'
Exec (@Sql)/*
a1 aa ab
---- ---- ----
00 01 02
*/http://topic.csdn.net/u/20080622/16/359d5894-a138-4bfc-96df-3ce58548b149.html
例如：
unpivot是由行转换为列，pivot是由列转换为行，比复杂的case when 好用很多,不知道是不用sql server2005的新特性以unpivot为例子:--在数据库中创建表，表名为acreate table a(id int identity(1,1),col1 datetime,col2 datetime,col3 datetime,
col4 datetime,col5 datetime,col6 datetime)
insert a values('2008-01-12','2008-02-12','2008-03-12','2008-04-12','2008-05-12','2008-06-12');
insert a values('2007-01-12','2007-02-12','2007-03-12','2007-04-12','2007-05-12','2007-06-12');
select * from a;
go--行列转换显示
select id,col,profile
from
a
unpivot
(
profile
for col in
([col1],[col2],[col3],[col4],[col5],[col6])
)
as unpvtgo详情：http://hi.baidu.com/bb3852/blog/item/b99e5a2bb48499ffe7cd406b.html