The shopping cart is a specialized case of database website. Database websites can manage, people, addresses,inventory, money or anything you could imagine.
If however your have a colllection of things to sell the shopping cart is the special database website you want.
Since shopping carts have been built so many times for so many buinesses it is no longer necessary to re-invent the wheel. We have available to us several pre-built shopping carts that we can modify to suit your needs.