title: Rails: Get next / previous record
body: <p>My app has Photos that belong to Users.</p>
  
  <p>In a photo#show view I'd like to show "More from this user", and show a next and previous photo from that user. I would be fine with these being the next/previous photo in <code>id</code> order or the next/previous photo in <code>created_at</code> order.</p>
  
  <p>How would you write that kind of query for one next / previous photo, or for multiple next / previous photos?</p>