sql 把不相等的值合并到一列里面

table：lcy_test

S_ID    C_ID    S_NAME
1    100    lcy
1    100    hxin
1    100    lixiang
2    200    lester
2    200    jacky
2    200    rocky

issue:how to get the result like blow:

1    100    lcy,hxin,lixiang
2    200    lester,jacky,rocky

solution:

SELECT s_id,c_id ,
       wmsys.wm_concat(s_name) ss
  FROM lcy_test group by s_id,c_id;

another reference:http://www.cnblogs.com/adslg/archive/2012/05/10/2493976.html