title: Django Select Query Time Diff
body: <p>I am trying to query a database table in django with, among others, the following columns:</p>
  
  <pre><code>id | start_time | end_time
  </code></pre>
  
  <p>Rather than getting the separate values for the two, can I just get the difference directly in a query?
  Something to this effect:</p>
  
  <pre><code>SELECT id, Diff(start_time, end_time) FROM myTable
  </code></pre>