--创建环境
create table test(iID int,content varchar(100))
insert into  test  select 100,'a' 
             union select 100,'b'
             union select 101,'c'
             union select 101,'d'
             union select 101,'e'

--创建一个合并的函数
create function contentDo(@id int)
returns varchar(8000)
as
begin
declare @str varchar(8000)
set @str=''
select @str=@str+','+cast(content as varchar) from test where iID=@id 
set @str=right(@str,len(@str)-1)
return(@str)
End
go

--调用自定义函数得到结果
select  iID,max(dbo.contentDo(iID)) as content  from test group by iID

--查询结果
iID   content  
------------
100   a,b    
101   c,d,e