Converting time difference to a given format in Oracle

Question

How do I convert EVENT_DATE_B - EVENT_DATE_A which is a number of days to string with HH:MM format?

Answer 1

If dates are differ only in time part you can use interval day to second. For instance:

SQL> select (to_date('25.12.12 15:37:32', 'DD.MM.YY HH24:MI:SS')
  2        - to_date('25.12.12 12:45:45', 'DD.MM.YY HH24:MI:SS')) day(0) to second(0) as Time
  3    from dual
  4  ;

TIME
-------------
+0 02:51:47

But obviously it will not always be the case. So you could write a long query to calculate different parts of time, but I think I would go with this simple function:

SQL> create or replace function DaysToTime(p_val in number)
  2  return varchar2
  3  is
  4    l_hours    number;
  5    l_minutes  number;
  6    l_seconds  number;
  7  begin
  8    l_Hours := 24 * p_val;
  9    l_minutes := (l_hours - trunc(l_hours)) * 60;
 10    l_seconds := (l_minutes - trunc(l_minutes)) * 60;
 11    return to_char(trunc(l_hours), 'fm09')  ||':'||
 12           to_char(trunc(l_minutes), 'fm09')||':'||
 13           to_char(trunc(l_seconds), 'fm09');
 14  end;
 15  /

Function created

And now the query would be:

SQL> select DaysToTime(to_date('25.12.12 15:37:32', 'DD.MM.YY HH24:MI:SS')
  2        - to_date('25.12.12 12:45:45', 'DD.MM.YY HH24:MI:SS')) as Time
  3    from dual
  4  ;

TIME
----------
02:51:47