1- master(id pk, document_date,....., net_amount). Net_amount is a calculated field but it's stored into the database. I know that storing a calculated value could be arguable but I need it for performance purposes. It should be populated with sum(total) + discount. Total is a column in the detail ig. Discount is a column in the master ig which has the net_amount.
2- detail ig(id pk, item_id, qty, price, total). Total= qty * price. And it's a calculated column too.
- When the user submits the page I need to do the calculation of the net_amount again on the server to avoid manipulating with it's value. The calculation is already done on the client side.