Oracle: Combine multiple results in a subquery into a single comma-separated value [duplicate]

Question

This question already has an answer here:

• How can I combine multiple rows into a comma-delimited list in Oracle? [duplicate] 11 answers

I'm trying to convert a single-columned subquery into a command-separated VARCHAR-typed list of values.

This is identical to this question, but for Oracle rather than SQL Server or MySQL.

Answer 1

There is an excellent summary of the available string aggregation techniques on Tim Hall's site.

Answer 2

I found this that seems to work. Thoughts?

SELECT SUBSTR (c, 2) concatenated
  FROM (SELECT     SYS_CONNECT_BY_PATH ( myfield, ',') c, r
              FROM (SELECT   ROWNUM ID, myfield,
                             RANK () OVER (ORDER BY ROWID DESC) r
                        FROM mytable
                    ORDER BY myfield)
        START WITH ID = 1
        CONNECT BY PRIOR ID = ID - 1)
 WHERE r = 1;

Answer 3

11.2 introduced LISTAGG, which unlike WM_CONCAT is documented. We are not on 11.2 yet, so we use a custom aggregate function.

Answer 4

Here's a blog that shows an Oracle query to work like MySQL's GROUP_CONCAT():

http://halisway.blogspot.com/2006/08/oracle-groupconcat-updated-again.html

Answer 5

SELECT deptno, wm_concat(ename) AS employees FROM emp GROUP BY deptno;

Reference: http://forums.oracle.com/forums/thread.jspa?messageID=1186901&#1186901