select b1.cid,wm_concat(b1.sname) from
(select c.ci_id cid,s.stu_name sname,instr(c.stu_ids,s.stu_id)
from pm_ci c,pm_stu s where instr(c.stu_ids,s.stu_id)<>0) b1 group by b1.cid;
select p.ci_id,max(stu_name) as STU_NAME
from (select c.ci_id,wm_concat(s.stu_name)
over(partition BY c.stu_ids order by s.stu_id) as stu_name
from pm_ci c,pm_stu s
where instr(c.stu_ids,s.stu_id) > 0) p
group by p.ci_id;
