title: Postgresql, sorting selected data(timestamp)
body: <p>Suppose I've done a select from two tables:</p>
  
  <pre><code>select a.frequency+b.lastrun
  from a, b where a.id = b.a_id;
  </code></pre>
  
  <p>And I get the output:</p>
  
  <pre><code>          ?column?
  ----------------------------
   2015-01-03 09:02:10.300201
   2015-01-09 09:02:10.300201
   2015-01-03 09:02:10.300201
   2015-01-02 21:02:10.300201
   2015-01-02 15:02:10.300201
   2015-01-09 09:02:10.300201
   2015-02-01 09:02:10.300201
   2015-01-03 09:02:10.300201
   2015-01-02 10:02:10.300201
   2015-01-03 09:02:10.300201
  </code></pre>
  
  <p>How do I sort this data by decrement ?</p>