time difference from datatime difference

i want time difference from startdate(format dttm) and enddate(format dttm).

this time difference is used in view record where its mapped to time datatype field.

example:

%DateTimeDiff(enddatetime,startdatetime) results is in seconds.

i want this in HH:MI format.

let me know if there any other meta function/delivered sql functions which can list out in time format (HH:MM:SS).

whatever function i am using its listing as seconds

to_char(enddatetime-startdatetime),'HH:MI' ....so on