Change separator of WM_CONCAT function of Oracle 11gR2

Question

Normally, WM_CONCAT is an aggregate function that return values from table separated by comma like here.

Suppose I have a table foo like this:

Answer 1

You might want to use LISTAGG.

SELECT col_id, 
       LISTAGG(col_text, '|') WITHIN GROUP (ORDER BY col_text) text
  FROM table1
 GROUP BY col_id

Output:

| COL_ID |            TEXT |
----------------------------
|    111 | This|a|is|test. |

SQLFiddle

UPDATE If you need to get distinct text values in a list

SELECT col_id, 
       LISTAGG(col_text, '|')
         WITHIN GROUP (ORDER BY col_text) text
  FROM 
(
  SELECT DISTINCT col_id, col_text
    FROM table1
)
 GROUP BY col_id

SQLFiddle