DECLARE @T TABLE
(
  tid INT
)
INSERT INTO @T
SELECT 1 UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4 

DECLARE @sql VARCHAR(50) 
SET @sql=''
SELECT @sql=@sql+','+CAST(tid AS VARCHAR(4)) FROM @T
PRINT right(@sql,LEN(@sql)-1)
/*

（所影响的行数为 4 行）

1,2,3,4

*/

------解决方案--------------------
SQL code
create table #Test(id int)
insert into #Test
select 1 union all
select 2 union all
select 3 union all
select 4

select * from #Test

declare @Str varchar(100)
set @Str=''
select @Str=@Str+','+cast(id as varchar(100)) from #Test
select stuff(@Str,1,1,'')
//1,2,3,4