title: date queries in phoenix sql?
body: <p>How do you select observations recorded in between now and 3 hrs ago i.e. now-3?
  There is a column which has timestamp and I am referring to that column in this question. I know phoenix has function <a href="http://forcedotcom.github.io/phoenix/functions.html#current_time" rel="nofollow">current_time()</a> which can give us the current time but how can I subtract 3 hrs from it?</p>
  
  <pre><code>select col1, col2, col3 
  from table 
  where col1 between current_time() and ???;
  </code></pre>
  
  <p>What should I use at <code>???</code> ?</p>