Oracle string aggregation by order

Custom aggregate function inside a package does not work??

LISTAGG Analytic Function in 11g Release 2 SELECT deptno, LISTAGG(ename, ',') WITHIN GROUP (ORDER BY ename) AS employees FROM emp GROUP BY deptno; WM_CONCAT Built-in Function (Not Supported) SELECT deptno, wm_concat(ename) AS employees FROM emp GROUP BY deptno; User-Defined Aggregate Function Specific Function Generic Function using Ref Cursor ROW_NUMBER() and SYS_CONNECT_BY_PATH functions in Oracle 9i COLLECT function in Oracle 10g https://oracle-base.com/articles/misc/string-aggregation-techniques http://www.oracle.com/technetwork/issue-archive/2006/06-jul/o46sql-083623.html