Help with ideas,query or formula to achieve the task

Guys i have data in a table with columns:

Stock Number|Description|Inventory Name|Year|Month|ADJUSTMENT|ISSUE|PT ISSUE|RECEIVE ADJ|RECEIVE FROM PO|RECEIVE XFER| RETURN|TRANSFER

i want to add the opening and closing balance columns to this table....... the closing balance column will be as follows

(SUM(ABS(RECEIVE_FROM_PO + RECEIVE_XFER + RECEIVE_ADJ + RETURN1)) - SUM(ABS(ADJUSTMENT + ISSUE + PT_ISSUE + TRANSFER))) as Closing Balance...for the 1st month as per stocknumber,year and inventoryname.

the opening balance will be the closing balance of the previous month + (SUM(ABS(RECEIVE_FROM_PO + RECEIVE_XFER + RECEIVE_ADJ + RETURN1)) of the current month minus SUM(ABS(ADJUSTMENT + ISSUE + PT_ISSUE + TRANSFER))) of the current in order to get the closing balance for the current month which will b passed to the next month to be the opening balance......

please help with the script to get the query right..thank you for help in advance guys...

Setting ABS() on balances is NOT the way to do it. Nothing will ever be NEGATIVE, except the final total. Store the values IN the table, and it's easier to calculate the latest one, rather than the last 10 million.