Remember Users Who Login via Facebook
What piece of data do I need to store in my database to remember a user who registered via Facebook? In other words, I've got Facebook login implemented (i .e. I can access your Facebook user profile), but I'd like to store information in my database and tie it to your user account (created via Facebook)
I've done a bunch of reading and most of the sources say I should be storing the OAuth ID in the database to use for this purpose. But I haven't seen a single page in Facebook's documentation that mentions anything about the OAuth ID. Now, I know Facebook has made some changes to how the login flow works, like switching to OAuth 2.0. So the sources that talk about the OAuth ID could be simply outdated. But, because I don't know how to do this yet, I can't tell if they're outdated or not.
I'm just really confused because the documentation seems to jump around a lot and I'm not a web developer by nature. Most of what I've done is desktop or database driven. So I really just don't know much about PHP and some of the common data flows present in web development. If anyone can help me figure this out and give me any other clarifying information on FB login, I would really appreciate it.