title: how to use the result from a case statement in a calculation
body: <p>I have a case statement that returns a date;</p>
  
  <pre><code>case when (ma.first_active_date is not null or ma.first_deemed_date is not null)
               then (least(nvl(ma.first_active_date,sysdate),nvl(ma.first_deemed_date,sysdate)))
               else (ma.status_date) end djf
  </code></pre>
  
  <p>How can i then calculate a count of years between the returned date and the sysdate?</p>