求一字符串，查询结果合并语句,该如何解决

--原数据col1  col2  col31      2     21      3     21      4     22      1     32      2     32      3     32      4     32      8     3------------------------------查询后数据col1  col2         col31     2,3,4        22     1,2,3,4,8    3    

select col1,  col2=stuff((select ','+ltrim(col2) from tb where col1=t.col1 and col3=t.col3 for xml path('')),1,1,'')from tb tgroup by col1,col3
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SQL code
--合并列值--原著：邹建--改编：爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)  2007-12-16  广东深圳--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。) --1. 创建处理函数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 create function dbo.f_str(@id int) returns varchar(8000) as begin     declare @r varchar(8000)     set @r = ''     select @r = @r + ',' + value from tb where [email protected]     return stuff(@r, 1, 1, '') end go -- 调用函数SELECt id, value = dbo.f_str(id) FROM tb GROUP BY id drop table tb drop function dbo.f_str /* id          value      ----------- ----------- 1          aa,bb 2          aaa,bbb,ccc （所影响的行数为2 行）*/ --2、另外一种函数. 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 --创建一个合并的函数create function f_hb(@id int) returns varchar(8000) as begin   declare @str varchar(8000)   set @str = ''   select @str = @str + ',' + cast(value as varchar) from tb where id = @id   set @str = right(@str , len(@str) - 1)   return(@str) End go --调用自定义函数得到结果：select distinct id ,dbo.f_hb(id) as value from tb drop table tb drop function dbo.f_hb /* 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) */ drop table tb
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SQL code
DECLARE @table TABLE(col1 INT,col2 INT,col3 INT)INSERT INTO @table        ( col1, col2, col3 )VALUES  ( 1, -- col1 - int          2, -- col2 - int          2  -- col3 - int          ),(1,3,2),(1,4,2),(2,1,3),(2,2,3),(2,3,3),(2,4,3),(2,8,3)SELECT col1,col2=STUFF((SELECT ','+CAST(col2 AS VARCHAR) FROM @table AS t1 WHERE t1.col1=t2.col1 FOR XML PATH('')),1,1,''),col3        FROM  @table AS t2GROUP BY col1,col3/*col1        col2           col3----------- -----------------------------1           2,3,4           22           1,2,3,4,8       3(2 行受影响)*/