title: ORA-00932: inconsistent datatypes: expected INTERVAL DAY TO SECOND got CHAR
body: <pre><code>SELECT COALESCE (
        (to_timestamp( '2014-09-22 16:00:00','yyyy/mm/dd HH24:MI:SS')
          -   ('2014-09-22   09:00:00' ,'yyyy/mm/dd HH24:MI:SS'))  
          - (to_timestamp( '2014-09-22 16:00:00','yyyy/mm/dd HH24:MI:SS')  
          - to_timestamp('2014-09-22 09:00:00.' ,'yyyy/mm/dd HH24:MI:SS')) 
         , '00:00') 
  FROM DUAL;
  </code></pre>
  
  <p>This is working in postgres but it is not working in oracle. </p>