I am creating an example database for a coffee shop. In the item table I have item name and item price. in order line item table I have quantity item price and extended price (quantity times price)
and in the sales order table i have subtotal, tax and total.

how do i have the database automatically insert item price in the order line item table and then calculate extended price. then take extended price from order line item and insert in subtotal of sales order table and the compute tax and total? or do i need to do this all by hand?
thanks
scott

Use triggers.