Query to group records

Question

hi,
i have records like this
supplier,product, persons involved
10,150,[email protected]
30,200,[email protected]
20,111,[email protected]
40,211,[email protected]
i want to write a query which displays values like this
10,30,40,[email protected]
for [email protected] if there are n number of suppliers all need to be concatenated as shown above.
can any one help me on this

Answer 1

Its a Typical String Aggregation Question.
[String Aggregation Techniques|http://www.oracle-base.com/articles/10g/StringAggregationTechniques.php] might be an interesting read for you.
SQL> With Test_Tab as
  2  (
  3  SELECT 10 supplier,150 product, '[email protected]' persons_involved FROM Dual
  4  UNION ALL
  5  SELECT 30,200,'[email protected]' FROM Dual
  6  UNION ALL
  7  SELECT 20,111,'[email protected]' FROM Dual
  8  UNION ALL
  9  SELECT 40,211,'[email protected]' FROM Dual
10  )
11  -- end of test data
12      SELECT   persons_involved,
13               LTRIM (
14                  MAX (SYS_CONNECT_BY_PATH (supplier, ','))
15                     KEEP (DENSE_RANK LAST ORDER BY curr),
16                  ','
17               )
18                  AS suppliers_involved
19        FROM   (SELECT   persons_involved,
20                         supplier,
21                         ROW_NUMBER ()
22                            OVER (PARTITION BY persons_involved ORDER BY supplier)
23                            AS curr,
24                         ROW_NUMBER ()
25                            OVER (PARTITION BY persons_involved ORDER BY supplier)
26                         - 1
27                            AS prev
28                  FROM   test_tab)
29    GROUP BY   persons_involved
30  CONNECT BY   prev = PRIOR curr AND persons_involved = PRIOR persons_involved
31  START WITH   curr = 1;
PERSONS_INVOLVE  SUPPLIERS_INVOLVED
[email protected]  20
[email protected]   10,30,40
2 rows selected.
SQL>Hope this helps.
Regards,
Jo