title: IMPALA date formats - Convert full timestamp to hourly timestamp
body: <p>I need to take a full timestamp column (Format: <code>YYYY-MM-DD HH:MM:SS.SSSS</code>) and convert it into hourly timestamp   (Format: <code>YYYY-MM-DD HH:00:00</code>)</p>
  
  <p>For example:
  I want to convert my existing date:</p>
  
  <pre><code>2016-02-26 04:00:07.766304000
  </code></pre>
  
  <p>into:</p>
  
  <pre><code>2016-02-26 04:00:00
  </code></pre>
  
  <p>I tried to use <code>unix_timestamp()</code> and <code>from_unixtime()</code>  function but it is too confusing :X</p>
  
  <p>Does someone know how to easily do it?</p>
  
  <p>Many Thanks for the helpers :)</p>