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

Question

I have this table view

UserName      Product     NumberPurchaces
--------      -------     ---------------
\'John Doe\'    \'Chair\'     4
\'John Doe\'    \'         


        

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.