timezone handling in oracle reports

HI,

We deal with timezone in our databases.  if it is EPT between Ist sunday of Apr to last sunday of Oct , then it is EST(current time) date +1/24 or else  est is same as as ept.

EPT EASTERN PREVAILING TIME
EST EASTERN STANDARD TIME

How can i use the function given below to be incorporated in the reports , that when the user pulls the est / ept from drop down list, it automatically gives the data for the corresponding timezone with the correct dates.


any help

Right now we have table hr_info which has time, time_ept as columns and is filled by a procedure with respective date and times and all our reports are joined to this table which is not very efficient like the the table is getting overfilled, or if something goes wrong in the table all the reports will not work.

sample report select:

select decode(:timezone, 'EPT', h.time_ept, h.time), u.unit from unit u, hr_info h
where u.date_time = h.time;


We have also have this function in our database.

function date_timezone_adjusted(input_date date, to_timezone varchar2 := 'EPT',other varchar2 := 'EST')
  return date is
  from_timezone  constant varchar2(3) := 'EST';
  date_adjusted  date;
begin
  date_adjusted := input_date;
  if upper(to_timezone) = 'EPT' then
      if input_date between date_start_dst(to_char(input_date,'RRRR'))
                        and date_end_dst(to_char(input_date,'RRRR')) then
      date_adjusted := new_time(input_date,from_timezone,'EDT');
      end if;
  elsif upper(to_timezone) = 'CST' then
    date_adjusted := new_time(input_date,from_timezone,upper(to_timezone));
  elsif upper(to_timezone) = 'CPT' then
    date_adjusted := new_time(input_date,from_timezone,'CST');
    if input_date between date_start_dst(to_char(input_date,'RRRR'))
                     and date_end_dst(to_char(input_date,'RRRR')) then
     date_adjusted := new_time(input_date,from_timezone,'CDT');
    end if;
  end if;
  if upper(other) = 'EPT' then
     if input_date between date_start_dst(to_char(input_date,'RRRR'))
                        and date_end_dst(to_char(input_date,'RRRR')) then
      date_adjusted := new_time(input_date,from_timezone,'CST');
       end if;
  end if;
    return date_adjusted;
end date_timezone_adjusted;



any help would be app