Mysql Or Form Suggestion

[smallc28]

I'm creating a test clothing site and i was wondering should I trying to use Mysql or POST / or GET Forms to transfer data from page to page

 

Let me explain what I'm trying to achieve here. I'm trying to let customers select which size they would like from Small, Medium, or Large. Once they've selected their size from the product page that information / data then gets transfer to the cart and loop over again so it doesn't go away when the customers continue to shop for more items.... anyways when they're finish I would then like the size to render out into paypal checkout so I the manager / admin would what size they'll need for shippment

 

If you prefer Myql how would I set this up

or POST / or GET Forms what step would I take for it to render out in paypal ?