Hi!Everyone,<BR><BR>Currently,I am implementing an on line computer sales system.<BR>I have problem to implement query for "The reorder level list<BR>for a particular time period on each product I sell".<BR><BR>I need to reduce the product qty_balance in the product table,<BR>each time customer purchase my product.Here is the tables involved:<BR><BR>1.Product table which include the reorder level field which I fixed to 200unit and the qty_balance which should be reduced each time a sales come across.The reduce amount is come from<BR>the sales_qty of the product in the sales_item table,e.g: product A have been sales 1 unit at day1,3 unit at day 2.Which means we will reduct 4 units from the qty_balance in the product<BR>table.<BR><BR>Note:product table&#039s primary key is prod_id<BR><BR>2.Sales_item table which include the sales_item_id(primary key) prod_id,sales_id,sales_quantity. <BR><BR>I am using vbscript and Access 97 and the query is perform on-line,not in the Access 97 locally.<BR><BR>Any solution for this problem? Thanks forward for any help! :)<BR><BR>From<BR>HELLOWORLD<BR>