If the value of total is unit_price * quantity then you don't need to store total. That's part second or third normal form, can't remember. You're creating a public or private package?

AnthonyVipond said:

If the value of total is unit_price * quantity then you don't need to store total. That's part second or third normal form, can't remember. You're creating a public or private package?

Thanks for your suggestion, I agree that storing total is not necessary.

This is for public package, next I'm want to create something like : Order / Invoice Package, Product Package, Payment Package, Customer Package, etc.

Btw, did you think that this package is good (useful) enough for now, so I can continue creating the other packages ?