ORACLE/SQL: wm_concat & order by

Question

I\'m using oracle 11 (not sure about the exact version, but since LISTAGG doesn\'t work, I suppose it\'s not release 2) through ODBC and crystal reports 2008.

Here

Answer 1

LISTAGG was introduced in 11g Release 2.

Therefore, in Oracle version prior to 11g where LISTAGG is not supported, you could use ROW_NUMBER() and SYS_CONNECT_BY_PATH functions.

See Oracle String Aggregation Techniques

SELECT task_card,
  LTRIM(MAX(SYS_CONNECT_BY_PATH(code,','))
  KEEP (DENSE_RANK LAST ORDER BY curr),',') AS zones
  FROM   (SELECT task_card,
                code,
                ROW_NUMBER() OVER (PARTITION BY fruit ORDER BY code) AS curr,
                ROW_NUMBER() OVER (PARTITION BY fruit ORDER BY code) -1 AS prev
         FROM   table_name)
  GROUP BY task_card
  CONNECT BY prev = PRIOR curr AND task_card= PRIOR task_card
 START WITH curr = 1;

NOTE

Never use WM_CONCAT since it is an undocumented feature and it has been removed from 12c version.

Any application which has had been relying on wm_concat function will not work once upgraded to 12c. Since, it has been removed. See Why not use WM_CONCAT function in Oracle?

SQL> select banner from v$version where rownum = 1;

BANNER
----------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production

SQL> SELECT object_name
  2  FROM dba_objects
  3  WHERE owner='WMSYS'
  4  AND object_name LIKE 'WM\_%' ESCAPE '\';

OBJECT_NAME
----------------------------------------------------------------------------
WM_REPLICATION_INFO
WM_RDIFF
WM_PERIOD
WM_PERIOD
WM_OVERLAPS
WM_MEETS
WM_LESSTHAN
WM_LDIFF
WM_INTERSECTION
WM_INSTALLATION
WM_GREATERTHAN
WM_EVENTS_INFO
WM_ERROR
WM_ERROR
WM_EQUALS
WM_DDL_UTIL
WM_DDL_UTIL
WM_CONTAINS
WM_COMPRESS_BATCH_SIZES
WM_COMPRESSIBLE_TABLES

20 rows selected.

SQL>

You will receive an “invalid identifier” error:

SQL> SELECT banner FROM v$version;

BANNER
----------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
PL/SQL Release 12.1.0.1.0 - Production
CORE    12.1.0.1.0      Production
TNS for 64-bit Windows: Version 12.1.0.1.0 - Production
NLSRTL Version 12.1.0.1.0 - Production

SQL> SELECT deptno, wm_concat(ename) FROM emp;
SELECT deptno, wm_concat(ename) FROM emp
               *
ERROR at line 1:
ORA-00904: "WM_CONCAT": invalid identifier

Therefore, there is no point relying on an undocumented feature which is no more made available in latest versions.