What ways are there to store information about an anonymous/guest user in a database?

Question

Our application has an online shop among other features, and users are normally requested to register before completing a sale, creating a unique customer_ID in the

Answer 1

The way I do it is : Not at all.

Simply put, let people pay through paypal or whatever you put as payment solution and get the data from there, automatically create the user and the order after the payment is processed using the provided API.

At that point you have all the information you need and can definitely store just enough for your statistics / e-spam marketing.

Keep it simple, require NOTHING, not even people to enter a customer id or an e-mail, and they'll all love it.

Doing that I still have every bit of information I could be interested in and the user experience is as fast/easy as can be.