title: ActiveRecord query to compare a time interval
body: <p>How to do something like this using ActiveRecord?</p>
  
  <pre><code>Reservation.where("start..finish &lt; 1 hour")
  </code></pre>
  
  <p><strong>start</strong> and <strong>finish</strong> are time records:</p>
  
  <pre><code>2.2.1 :009 &gt; Reservation.last.start.class
    Reservation Load (1.1ms)  SELECT  "reservations".* FROM "reservations"  ORDER BY "reservations"."id" DESC LIMIT 1
    Reservation Load (1.1ms)  SELECT  "reservations".* FROM "reservations"  ORDER BY "reservations"."id" DESC LIMIT 1
   =&gt; ActiveSupport::TimeWithZone 
  </code></pre>
  
  <p>Thanks.</p>