SELECT

   EXTRACT(DAY FROM (sysdate-to_date('2012-03-29 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )

   || ' days '

   || EXTRACT(HOUR FROM (sysdate-to_date('2012-03-29 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )

   || ' hours'

   || EXTRACT(MINUTE FROM (sysdate-to_date('2012-03-29 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )

   || ' minute'

   || EXTRACT(SECOND FROM (sysdate-to_date('2012-03-29 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )

   || ' second' "Interval"

FROM DUAL;

SELECT

   EXTRACT(DAY FROM (sysdate-to_date('2013-09-01 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )*24+

   EXTRACT(HOUR FROM (sysdate-to_date('2013-09-01 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )

   || ' hours'

   || EXTRACT(MINUTE FROM (sysdate-to_date('2013-09-01 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )

   || ' minute'

   || EXTRACT(SECOND FROM (sysdate-to_date('2013-09-01 00:00:00','YYYY-MM-DD HH24:MI:ss')) DAY TO SECOND )

   || ' second' "Interval"

FROM DUAL;