Oracle PIVOT with Mulitpl Years (mulitple tables)

I am working on a project which is asking for a specific format of reporting. Until now I was able to get this done in ACCESS, but since the data is now in Oracle I can do much better things. I have been checking all the groups on how to create a PIVOT and I am getting the general idea here, however maybe somebody can give some good guidelines on how to achieve the following.

1. The data is stored in one big datawarehouse and all linking tables will not be included (these tables will be linked later in Crystal, like name, adres, product description etc.
2. The normal display for this request is that I need to compare several years (in detail by month) to see progress in numbers and Percentages (crystal)

Like:
Customer (this actually a department)
PRDGRP (this is group) Jan Year 1 Jan Year 2 Feb Year 1 Feb Year 2

H01                         100         120          90        101

I have 2 ideas on achieving this, one is a view with the decode command used or I will create a procedure that will fill another table with these records. The number of records in the table are 2 million (and not all very clean so it need to have some filter tweaking to get the data right)

I need to the most simple version of this because this table also need to work on money and quantity (the report will show either Sales in € or in quantities) Received on Thu Nov 18 2004 - 00:42:37 CST