sales of the same item resulting in duplicate of stock entries

Hi,


I made 2 simple tables

• stock
• Sales

where sales-to-stock is many-to-1 with outer join all stocks displayed.


I put item A @ 20units into Stock and sell (using autopopulate form) item A @ 5 units now and @ 7 units later.


however in the report, instead of recording it as item A left @ 8units because 20-7-5. i got a duplicate entry of the stock item where item A left @ 28units because (20-7) + (20-5) = 28.


my guess is because i link sales to stock, everytime i input the sales for the same stock, i received duplicate entry for stock. however i need to link it for the sake of autopopulating form.


please help me on this.
thank you.

sales of the same item resulting in duplicate of stock entries