title: PostgreSQL: drop fraction of second from interval
body: <p>My query:</p>
  
  <pre><code>SELECT AVG(time_out - time_in) from time_table
  </code></pre>
  
  <p>Result:</p>
  
  <pre><code>3 days 17:21:21.062313
  </code></pre>
  
  <p>The problem is, the computed average also has the fractional part of a second .062313, which I don't need, so I must drop it. How do I do that?</p>