title: how to find the duration between two dates
body: <p>I want to find the duration between the two date columns. For this i used the DATEDIFF function to find number years and months separately but wanted both results in single column.
  The two columns are given below.  </p>
  
  <pre><code>start_dt      |    end_dt
  06-Oct-2009      15-Jul-2011  
  </code></pre>
  
  <p>Result which needed </p>
  
  <pre><code>Duration(years.months)
  2.3
  </code></pre>