How to count the number of PRODUCTS bought in a cart.
A shopping cart has a table called "cart" where the customer's selections are stored.
The customer buys 1 item of Product C, 2 items of Product H and 3 items of Product T.
I need to be able to count the number of PRODUCTS bought NOT the number of items. i.e. the answer here is 3.
What is the EASIEST way to do this?