Closing Balance as Opening Balance

I want to carry forward the closing balance as opening balance in the folowing month below is the sql code i have done. Please help agent....Thank you in advince..

select StockNumber,InventoryName,Year1,Month1,RECEIVE_FROM_PO,RECEIVE_XFER,RECEIVE_ADJ,
_RETURN,ADJUSTMENT,ISSUE,PT_ISSUE,TRANSFER, SUM(ABS(RECEIVE_FROM_PO + RECEIVE_XFER + RECEIVE_ADJ + _RETURN))
- SUM(ABS(ADJUSTMENT + ISSUE + PT_ISSUE + TRANSFER))
as BALANCE, BALANCE as OPENING_BAL
into final2
from dbo.drug_summary$
GROUP BY StockNumber,InventoryName,Year1,Month1,RECEIVE_FROM_PO,RECEIVE_XFER,RECEIVE_ADJ,
_RETURN,ADJUSTMENT,ISSUE,PT_ISSUE,TRANSFER,BALANCE