这样的数据结构
ID  COL1  COL2 COL3
1    1     2    3
2    1     2    3
3    1     1    2 

要显示的结果
ID  COL1  COL2 COL3
1,2  1     2    3
3    1     1    2
这个SQL要怎么写啊 

select id=stuff((select ','+rtrim(id) from tb 
       where col2=a.col2 and col3=a.col3 and col4=a.col4 from xml path('')),1,1,''),
       col2,col3,col4
from tb group by col2,col3,col4

------解决方案--------------------
 select id=stuff((select ','+CONVERT(varchar,id) from tb where tb.col1=a.col1 and col2=a.col2
  and col3=a.col3 for xml path('')),1,1,'') ,col1,col2,col3 from tb a group by col1,col2,col3;