===== WM_CONCAT is gone 12c =====
Hi tom,
when i tried use this wm_concat() function in 12c i'm getting this error can you briefly explain?

ORA-00904: "WM_CONCAT": invalid identifier
00904. 00000 - "%s: invalid identifier 
and we said...
WM_CONCAT is gone in 12c.

Use LISTAGG instead
<code sql>
SQL> select deptno, listagg(ename, ',') within group (order by ename) as employees
  2  from   emp
  3  group by deptno;

    DEPTNO EMPLOYEES
---------- ------------------------------------------------------------
        10 CLARK,KING,MILLER
        20 ADAMS,FORD,JONES,SCOTT,SMITH
        30 ALLEN,BLAKE,JAMES,MARTIN,TURNER,WARD
</code>