同列什的文本不能合并在一起

create table ym
(col1 int, col2 int, col3 varchar(3))insert into ym
select 1, 1, 'A' union all
select 1, 1, 'B' union all
select 1, 2, 'C' union all
select 1, 3, 'D' union all
select 1, 3, 'E'
select a.col1,a.col2,
stuff((select ','+col3 from ym b
       where b.col1=a.col1 and b.col2=a.col2
       for xml path('')),1,1,'') 'col3'
from ym a
group by  a.col1,a.col2你参考一下，自己改改吧