I'm just getting the FB Id and I put it on Custom profile data.
I'm not sure if placing it on the users table is the best way to do it?
But having such in the Custom profile field allows phpBB owners to utilize the built-in feature of CPF wherein they can show it in their viewtopic pages.
In the same manner, an avatar can be fetched too since it is publicly available as long as you have an FB user id or FB username.
What data do you grab from FB ? Is it possible to use FB profile picture as avatar and fill the Location, Interests and other fields in phpbb using data from FB ?
Do you think it's a good idea to fetch location too and save it on the phpbb table? I'll just check FB pages whether making users agree with my phpBB app to fetch offline data (FB permissions) will save phpBB owners another database column for facebook data.
My point of focusing on the FB id is so that even if customers change info, nothing has to be done on the phpBB side anymore since seldom would a user delete his FB account.