title: HP Vertica SQL timestamp to number
body: <p>I'm trying to aggregate timestamps using <code>STDDEV</code> and I keep getting the error that it doesn't exist for the argument I'm providing it. Is there a way to convert timestamps in HP Vertica SQL to a int or number format or even unix timestamp. </p>
  
  <p>I've tried:</p>
  
  <pre><code>select a, STDDEV(timestamp1) 
  from mytable 
  group by a
  </code></pre>
  
  <p>I get the error no function matches the given name an argument. I've used stddev before. I looked at the actual table and saw that though it's a time stamp field it looks to be represented as a date.</p>