Time difference

Query to get the time different between 2 date columns

select floor(((end_time - start_time)*24*60*60)/3600)
       || ' HOURS ' ||
       floor((((end_time - start_time)*24*60*60) -
       floor(((end_time - start_time)*24*60*60)/3600)*3600)/60)
       || ' MINUTES ' ||
       round((((end_time - start_time)*24*60*60) -
       floor(((end_time - start_time)*24*60*60)/3600)*3600 -
       (floor((((end_time - start_time)*24*60*60) -
       floor(((end_time - start_time)*24*60*60)/3600)*3600)/60)*60)))
       || ' SECS ' time_difference
from sub_email_jobs;