sql - Pivot / Crosstab Query in Oracle 10g (Dynamic column number)

Question

I have this table view

UserName      Product     NumberPurchaces
--------      -------     ---------------
'John Doe'    'Chair'     4
'John Doe'    'Table'     1
'Jane Doe'    'Table'     2
'Jane Doe'    'Bed'       1

How can I create a query that will provide this pivot view in Oracle 10g ?

 UserName   Chair   Table   Bed
 --------   -----   -----   ---
 John Doe   4       1       0
 Jane Doe   0       2       1

Any way to do it dynamically? I saw so many approaches (decode, PL/SQL loops, unions, 11g pivot)

But I've yet to find something that will work for me based on the above example

---

Edit: I don't know the number or type of products in development time so this has to be dynamic

Answer 1

Oracle 11g is the first to support PIVOT/UNPIVOT, so you have to use:

  SELECT t.username,
         MAX(CASE WHEN t.product = 'Chair' THEN t.numberpurchases ELSE NULL END) AS chair,
         MAX(CASE WHEN t.product = 'Table' THEN t.numberpurchases ELSE NULL END) AS tbl,
         MAX(CASE WHEN t.product = 'Bed' THEN t.numberpurchases ELSE NULL END) AS bed
    FROM TABLE t
GROUP BY t.username

You could use DECODE, but CASE has been supported since 9i.