title: How to find difference b/w TIMESTAMP format values in Oracle?
body: <p>I have two <code>timestamp</code> columns: <code>arrTime</code> and <code>depTime</code>.
  I need to find the number of munites the bus is late.
  I tried the following: </p>
  
  <pre><code>SELECT RouteDate, round((arrTime-depTime)*1440,2) time_difference
  FROM ...
  </code></pre>
  
  <p>I get the following error: <code>inconsistent datatype . expected number but got interval day to second</code></p>
  
  <p>How can i parse the nuber of minutes?</p>
  
  <p>If i simply subtract: <code>SELECT RouteDate, arrTime-depTime)*1440 time_difference</code>
  The result is correct but not well formatted:</p>
  
  <pre><code> time_difference
    +00000000 00:01:00 0000000
  </code></pre>