sql subtract
I think this is what you're looking for. NEW_BAL is the sum of QTYs subtracted from the balance: SELECT master_table.ORDERNO, master_table.ITEM, SUM(master_table.QTY), stock_bal.BAL_QTY, (stock_bal.BAL_QTY - SUM(master_table.QTY)) AS NEW_BAL FROM master_table INNER JOIN stock_bal ON master_bal.ITEM = stock_bal.ITEM GROUP BY master_table.ORDERNO, master_table.ITEM If you want to update the item balance with the new balance, use the following: UPDATE stock_bal SET BAL_QTY = BAL_QTY - (SELECT SUM(QTY) FROM master_table GROUP BY master_table.ORDERNO, master_table.ITEM) This assumes you posted the subtraction backward; it subtracts the quantities in the order from the balance, which makes the most sense without knowing more about your tables. Just swap those two to change it if I was wrong: (SUM(master_table.QTY) - stock_bal.BAL_QTY) AS NEW_BAL
