Thank for this thread, it give me an idea to design my accounting database.

I have another problem, when i need to average the cost of goods. (when stock in / return).

At the end of the month. The P&L for the closing stock:
If i use the 1200(qty in hand) @ 4.0941 = 4912.92

If i use the (opening stock + purchases) - (sales's cost) = 49.12.94

Both are not tally. In accounting practice, which method should i use?

** Noted: My client request to average the cost for (stock in / stock return)

All the calculation above is on cost, not selling price.