my problem is this,i am using a barcode reader to enter data in msflexgrid,then my quantity column,automatically add 1 if it has the same item to enter.if a user made a mistake like for example,entering item more than the order of customer.like if a customer order only 3 same item then the user entered 5,how can i subtract that existing quantity of item in msflexgrid quantity column and update the database..