title: convert bigint to date so that I can use in where clause
body: <p>My date is of type bigint.
  How can I select date?</p>
  
  <p>Typical query to get date is like this</p>
  
  <pre><code>select date from my_table where date&lt;='20150101'
  </code></pre>
  
  <p>The problem right now is, date is of type bigint</p>