title: Twitter OAuth + auto login + MYSQL
body: <p>I'm using <a href="https://github.com/abraham/twitteroauth" rel="nofollow">https://github.com/abraham/twitteroauth</a> library. I already created my app on Twitter, the callbacks are working fine (even on localhost), but one thing that is bugging me is HOW the auto-login happens? I know there's "user_id" that is stored in the MYSQL database, along with oauth_token and oauth_token_secret, but how do I obtain user_id as soon as the user enters the site, so I can query the database to see if it already exists and what not, without having to popup the authorize twitter popup then reaching the callback, over and over again?</p>
  
  <p>I've seen a lot of questions like this one, but no one ever answered it in a satisfying way.</p>