sql 2008怎么实现mysql中group_concat

sql 2008如何实现mysql中group_concat？
列如有表TAB!：
A B
1 aa
2 bb
1 cc
2 dd
3 ff 

 想要得到查询结果 
 1 aa,cc
 2 bb,dd
 3 ff 最好能一条语句查询，如果要写函成数，能不能写成通用的，各表都能用

[解决办法]

SQL code

-- SQL Server 2005select a, stuff((select ','+b from tab where a=t.a for xml path('')),1,1,'') bfrom tab t group by a;
[解决办法]
SQL code
/*标题：按某字段合并字符串之一(简单合并)作者：爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)时间：2008-11-06地点：广东深圳描述：将如下形式的数据按id字段合并value字段。id    value----- ------1     aa1     bb2     aaa2     bbb2     ccc需要得到结果：id     value------ -----------1      aa,bb2      aaa,bbb,ccc即：group by id, 求 value 的和（字符串相加）*/--1、sql2000中只能用自定义的函数解决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')gocreate function dbo.f_str(@id varchar(10)) returns varchar(1000)asbegin  declare @str varchar(1000)  select @str = isnull(@str + ',' , '') + cast(value as varchar) from tb where id = @id  return @strendgo--调用函数select id , value = dbo.f_str(id) from tb group by iddrop function dbo.f_strdrop table tb--2、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')goselect id, [value] = stuff((select ',' + [value] from tb t where id = tb.id for xml path('')) , 1 , 1 , '')from tbgroup by iddrop table tb--3、使用游标合并数据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')godeclare @t table(id int,value varchar(100))--定义结果集表变量--定义游标并进行合并处理declare my_cursor cursor local forselect id , value from tbdeclare @id_old int , @id int , @value varchar(10) , @s varchar(100)open my_cursorfetch my_cursor into @id , @valueselect @id_old = @id , @s=''while @@FETCH_STATUS = 0begin    if @id = @id_old       select @s = @s + ',' + cast(@value as varchar)    else      begin        insert @t values(@id_old , stuff(@s,1,1,''))        select @s = ',' + cast(@value as varchar) , @id_old = @id      end    fetch my_cursor into @id , @valueENDinsert @t values(@id_old , stuff(@s,1,1,''))close my_cursordeallocate my_cursorselect * from @tdrop table tb