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

Question

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

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 2

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

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.