Backorders should already be reflected in the current balance and do not need backing out. Supplier backorders are product you have not received from your supplier. Backorders to the customers are product not yet delivered to the customer. The system I developed does not decrement the current balance until backorders or filled. Nor does it increment the current balance until backorders are received from the supplier. I would think this is how all inventory systems work [or should, IMHO].

By adjustments I take it you mean losses due to shoplifting, theft, etc., and balancing gains and losses due to accidental substituting of a product for another [wrong item pulled to fill an order so on-hand for one item is short 1 and the other is over 1].

>and adjustments and backorders
>
>>>Hi,
>>> I am developing POS (Point od Sales) system. My client request to have feature that able to view the stock balance at the particular period such as 2 months ago or may be 2 days ago.
>>> How could I retrieve the stock qty at certain period? Should I re-calculate the total purchase, total return, total sales of items in order to get these stocks balance?? What do you do for these?
>>>
>>>Thank you
>>
>>Think of it as a checkbook. From the current Quantity [balance], you have to subtract any product orders received by the client from their suppliers [deposits]. You have to add the net quantity sold to the customers [withdrawals]. This means you have to have a way of tracking, by date, the orders the client places and receives that restock his inventory as well as track all sales and returns by the customers.