Calculating Column Values

Hi, this is my problem. The query listed below gets a list of employees asigned to a project, to a customer and to a business unit (the Dimension field). The last two fields are the start date and the end date.


select
P.DIMENSION, P.CUSTACCOUNT, C.NAME as CUSTOMERNAME, PE.PROJID, P.NAME as PROJNAME, PE.EMPLID, E.NAME as EMPLNAME,
PE.FECHAASIGNACION, PE.FECHADESASIGNACION
from
PROJVALEMPLPROJSETUP PE, EMPLTABLE E, PROJTABLE P, CUSTTABLE C
where
PE.PROJID = P.PROJID and PE.EMPLID = E.EMPLID and P.CUSTACCOUNT = C.ACCOUNTNUM and (PE.FECHAASIGNACION >= '01/01/2007'
and PE.FECHADESASIGNACION >= '01/01/2007')
order by
P.DIMENSION, P.CUSTACCOUNT, PE.PROJID, PE.EMPLID


I need to get a listing showing how many employees started or ended their projects every months in the following format:

Business UNIT CLIENT PROJECT STARTING TOTAL JANUARY FEBRUARY .. TOTAL VARIATION
--------------------------------------------------------------------------------------------------------
1 1 1 25 3 -2 26 1


Starting total refers to all the employees that have a starting date before 1/1/2007 and a ending date after 1/1/2007

The monthly columns would be the total of employees with a starting date (+1) or ending date (-1) in that month.

The total column is the starting total plus the monthly totals.

And the variation is the difference of the total with the starting total.

Any ideas?

Thanks a lot.