Recursive Reference in SQL Calc

given the following table structure

id,...,date_initiated, date_closed,...

how would one do the following calculation for a date range, grouped by month/year for charting purposes:

count pending this month =

       count pending last month + 
            count initiated this month -
                 count closed this month

assuming the first month's count pending is:

count initiated first month - count closed first month

Thanks!!
Ian Received on Thu Mar 14 2002 - 18:52:46 CST