Procedure needed for this scenario

Question

There are three tables.
serial,product and service
some of the fields and how they are related are shown below:
=======================================================
serial               product               service
=======================================================
ip_addr                              item_id
               prod_id(P) --------->     prod_id(F)
                    1-many               
serial_no(P) ---------> serial_no(F)
          1-many
=======================================================
P-Primary Key
F-Foreign Key
=======================================================
relationship between ip_addr and item_id is many-to-many.
based on the item_id we have to categorize ip_addr.
if item_id 684 it is demo a/c
if item_id = 650,652,654,892,894,896,898,900,902,1560,1562,1564,1566,1568,1570
then this is categorized as high rate account.
if it is 644,646 it is stat a/c
other than these item_id are comes under standard a/c
So if a ip_addr has xyz and 684 it should be counted as demo and not standard.
Next you should have for high rate but that units should not have demo.
Next you should have stat a/c but that units should not have high rate and demo
next you should have std a/c but that should not have stat ,high rate and demo.
So, the priority for the account should be demo then high rate then stat then std.
If ip_addr has been categorized to any one of these categories it should not be
processed again.
In other words, ONE IP_ADDR SHOULD ONLY FALL IN ONE OF THE ABOVE CATEGORIES.
The final output should be the no. of ip_addr and the list of ip_addr in each category
namely demo,high rate,stat and std.
Please help me out.
Thanks in advance
~Chandru

Answer 1

To be frank I can't be bothered to create a whole bunch of test data for this, but it has worked with one row in each table :P
SELECT serial.ip_addr, b.cat
FROM serial,
(SELECT a.ip_addr, a.cat, rownum ranking
FROM (SELECT serial.ip_addr
, decode(service.item_id, 684, 'demo'
, 650, 'high rate'
, 652, 'high rate'
, 654, 'high rate'
, 892, 'high rate'
, 894, 'high rate'
, 896, 'high rate'
, 898, 'high rate'
, 900, 'high rate'
, 902, 'high rate'
, 1560, 'high rate'
, 1562, 'high rate'
, 1564, 'high rate'
, 1566, 'high rate'
, 1568, 'high rate'
, 1570, 'high rate'
, 644, 'stat'
, 646, 'stat'
, 'std') cat
FROM service, product, serial
WHERE serial.serial_no = product.serial_no
AND product.prod_id = service.prod_id ) a
ORDER BY decode (a.ip_addr, a.cat, 'demo', 1, 'high rate', 2, 'stat', 3, 4) ) b
WHERE serial.ip_addr = b.ip_addr
AND b.ranking = 1
Cheers, APC