select count(*) into days from (select dt
from(
    select to_date(:p1_from_date, 'DD-Mon-YYYY')

select empid,trunc(dt) as Dat, 
to_char(min(dt),'hh:mi am') as Firstintime, 
to_char(max(dt),'hh:mi am') as Lastouttime, 
to_char(trunc(sysdate) + (max(dt) - min(dt)),'hh24:mi') as TotalHours 
from trans 
group by trunc(dt),empid

select empid,trunc(dt) as Dat,
min(dt) as Firstintime,
max(dt) as Lastouttime,
to_number(max(dt) - min(dt))*24 as TotalHours 
from trans
group by trunc(dt),empid

empid                            dat
======                         ====
101                              4/9/2012 9:48:54 AM
101                               4/9/2012 9:36:28 AM
101                                4/9/2012 6:16:28 PM

create or replace trigger inserttrigger2
before insert on t1
referencing old as old new as new
for each row
declare
to_date date;
from_date date;
no_of_days number(2);
remaining_days number(2);

begin
to_date := :new.to_date;
from_date := :new.from_date;
no_of_days