急！求教高手oracle9i将多列合并为一列

Question

SQL> create table temp(index_id integer,class_name varchar2(20));表被创建SQL> select  * from temp;                               INDEX_ID CLASS_NAME
--------------------------------------- --------------------
                                      1 aaaaaaaa
                                      1 bbbbbbbb
                                      1 ccccccccc
                                      2 dddddddd
                                      2 rrrrrrrtyyyyy
                                      2 fffffffffhhhhh
                                      3 uuuuuuuuuu
                                      3 uuuuuuuuu
要求得到的结果为：按index_id分组group by index_id,得到的新表为：
  index_id        新字段
    1             aaaaaaaa，bbbbbbbb，ccccccccc
    2             dddddddd，rrrrrrrtyyyyy，fffffffffhhhhh
    3             uuuuuuuuuu，uuuuuuuuu
可否实现？      

Answer 1

select INDEX_ID,max(substr(sys_connect_by_path(CLASS_NAME,','),2))
 from temp
 start with index_id=1 and prior index_id=index_id
 group by index_id

Answer 2

select INDEX_ID , wm_concat(CLASS_NAME)
 from temp group by INDEX_ID