title: DateTime on Where Clause Oracle
body: <p>it seems there are lot of query syntax to fetch data on oracle database, here I just want to ask about the query that works fine but I cant understand at all. The query is :</p>
  
  <pre><code>Select
  ....
  From
  ...
  Where
  TO_CHAR(TO_DATE('01/01/1970 00:00:00', 'MM/DD/YYYY HH24:MI:SS') +
  (create_date  / ( 60 * 60 * 24 )),
  'MM/DD/YY HH24:MI:SS') = '06/30/14 21:41:11'
  ;
  </code></pre>
  
  <p>From the query above it's work fine. But I cant understand why there's <strong>TO_DATE('01/01/1970 00:00:00', 'MM/DD/YYYY HH24:MI:SS</strong> and <strong>(create_date  / ( 60 * 60 * 24 )),
      'MM/DD/YY HH24:MI:SS')</strong> </p>
  
  <p>on the <em>create_date</em> fields it show unix datetime such as 1404164471</p>
  
  <p>Can anybody explain about this?</p>
  
  <p>thanks in advance</p>