合并列值 
--*******************************************************************************************
表结构，数据如下： 
id    value 
----- ------ 
1    aa 
1    bb 
2    aaa 
2    bbb 
2    ccc 

需要得到结果： 
id    values 
------ ----------- 
1      aa,bb 
2      aaa,bbb,ccc 
即：group by id, 求 value 的和（字符串相加） 

1. 旧的解决方法(在sql server 2000中只能用函数解决。) 
--=============================================================================
create table tb(id int, value varchar(10)) 
insert into tb values(1, 'aa') 
insert into tb values(1, 'bb') 
insert into tb values(2, 'aaa') 
insert into tb values(2, 'bbb') 
insert into tb values(2, 'ccc') 
go 
--1. 创建处理函数 
CREATE FUNCTION dbo.f_strUnite(@id int) 
RETURNS varchar(8000) 
AS 
BEGIN 
    DECLARE @str varchar(8000) 
    SET @str = '' 
    SELECT @str = @str + ',' + value FROM tb WHERE id=@id 
    RETURN STUFF(@str, 1, 1, '') 
END 
GO 
-- 调用函数 
SELECt id, value = dbo.f_strUnite(id) FROM tb GROUP BY id 
drop table tb 
drop function dbo.f_strUnite 
go
/* 
id          value      
----------- ----------- 
1          aa,bb 
2          aaa,bbb,ccc 
（所影响的行数为 2 行） 
*/ 
--===================================================================================
2. 新的解决方法(在sql server 2005中用OUTER APPLY等解决。) 
create table tb(id int, value varchar(10)) 
insert into tb values(1, 'aa') 
insert into tb values(1, 'bb') 
insert into tb values(2, 'aaa') 
insert into tb values(2, 'bbb') 
insert into tb values(2, 'ccc') 
go 
-- 查询处理 
SELECT * FROM(SELECT DISTINCT id FROM tb)A OUTER APPLY( 
        SELECT [values]= STUFF(REPLACE(REPLACE( 
            ( 
                SELECT value FROM tb N 
                WHERE id = A.id 
                FOR XML AUTO 
            ), ' <N value="', ','), '"/>', ''), 1, 1, '') 
)N 
drop table tb 

/* 
id          values 
----------- ----------- 
1          aa,bb 
2          aaa,bbb,ccc 

(2 行受影响) 
*/ 

--SQL2005中的方法2 
create table tb(id int, value varchar(10)) 
insert into tb values(1, 'aa') 
insert into tb values(1, 'bb') 
insert into tb values(2, 'aaa') 
insert into tb values(2, 'bbb') 
insert into tb values(2, 'ccc') 
go 

select id, [values]=stuff((select ','+[value] from tb t where id=tb.id for xml path('')), 1, 1, '') 
from tb 
group by id 

/* 
id          values 
----------- -------------------- 
1          aa,bb 
2          aaa,bbb,ccc 

(2 row(s) affected) 

*/

------解决方案--------------------
SQL code
select 
COl1,
col2=stuff((select ','+col2 from t1 where COl1=a.COl1 for xml path('')),1,1,'')
from t1 as a
group by col1

------解决方案--------------------
SQL code
create table tb(c1 int,c2 varchar(10))
insert into tb select 35,'AAA'
insert into tb select 47,'AAA'   
insert into tb select 51,'AAA'   
insert into tb select 36,'BBB'
insert into tb select 35,'BBB'  
insert into tb select 47,'BBB'
go
select c2,stuff((select ','+LTRIM(c1) from tb where c2=a.c2 for xml path('')),1,1,'')c1 from tb a group by c2
/*
c2         c1
---------- ----------------------------------------------------------------------------------------------------------------
AAA        35,47,51
BBB        36,35,47

(2 行受影响)

*/
go
drop table tb

------解决方案--------------------
SQL code
use Tempdb
go
--> --> 
 
declare @T table([Col2] int,[Col1] nvarchar(3))
Insert @T
select 35,N'AAA' union all
select 47,N'AAA' union all
select 51,N'AAA' union all
select 36,N'BBB' union all
select 35,N'BBB' union all
select 47,N'BBB'
 
select 
COl1,
col2=stuff((select ','+RTRIM(col2) from @T where COl1=a.COl1 for xml path('')),1,1,'