Change Stock

[moj6054]

I have more product.

I have this tables(categories:For Sub Product Productetails of Product and link to categories

Order:Order Information OrderItems:Link to product(Duplicated this table and rename ItemPurchased) and a filed cLineTotal=Qty(product)* price

Invoices:Invoices information InvoiceItem:Link to product(duplicated this table and rename ItemSold) and a field clinetotal=Qty*Price

)

and in the order(TO) a field cTotalOrder=Sum(cLineTotal)

and in the Invoice(TO) a field cTotalInvoice=Sum(cLineTotal)

 

in product: a field cStockLevel=Qty+Sum(Qty::ItmePurchased)-Sum(Qty::ItemSold)

 

I need to replace cStockLevel value with Product Qty for next progress.

How I can do this?