Query (connect by/string agregation)

Question

Hi
Can anybody give me an example of query
ID VAL
1 A
1 B
1 C
Output: 'A,B,C'
Thanks.
Edited by: Bolev on Feb 3, 2010 5:10 PM

Answer 1

Hi,
Pivot produces separate columns for each val, and you have to know how many there will be.
String Aggregation provides one column, and does not need to know how many vals there will be:
WITH     got_rnum     AS
     SELECT     id
     ,     val
     ,     ROW_NUMBER () OVER ( PARTITION BY  id
                               ORDER BY          val
                       ) AS rnum
     FROM    table_x
SELECT     id
,     LTRIM ( SYS_CONNECT_BY_PATH (val, ',')
           )     AS val_list
FROM     got_rnum
WHERE     CONNECT_BY_ISLEAF     = 1
START WITH     rnum     = 1
CONNECT BY     rnum     = PRIOR rnum + 1
     AND     id     = PRIOR id
;