Facebook第二次验证用户

Question

I'm developing a PHP/MYSQL powered system, and have facebook, twitter and normal login.

Each user DB record has 'type' assigned to it, which defines how they logged in, but here's where I run into a logical problem,

I record their email, username in the DB once they log into my website.

Now let's say they access the site through a different laptop and click 'login with facebook', how do I make sure that they are the same person? As you can change email and username on facebook. Do I record their user id from facebook or?

Any help would be apreciated

Answer 1

Facebook have the unique userid. You can use that one to identify the same person.