Is facebook connect supposed to replace traditional user account creation?

I have a game application for mobile. When signing new users up, I put them in a database table like:

id | email | username | password_hashed | etc

I'm not understanding what we do if we use facebook connect to let them "sign up" to the app. Is the idea to allow them to skip filling out a signup form altogether? Would I modify the user table to look like:

id | email       | username | password_hashed | optional_fb_id
---------------------------------------------------------------    
 1   foo@foo.com    foo          xyz              null
 2   null           grok         null             789

The idea being that if they sign up the "normal" way, th开发者_开发百科ey'd have to give me their email address, and a password for their account (row 1). If they signup using facebook connect, I don't need their email or a password, I just store their facebook id instead? (row 2).

Thanks

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You would likely store the Facebook user ID to associate the user with their Facebook account. I would suggest checking out the documentation that Facebook provides regarding the Registration plugin.