Trigger Difference Betwwen Two Time- How?

Question

Hi all, I have One table,
Date format :dd/mm/yyyy
Table name: Time_Calculation
Time1--------------------------Time2----------- Diff_Time
8/9/2006 1:10:57 PM----9/9/2006 1:10:58 PM-----24:00:01
I want to create the trigger that can calculate the diffrence time between time2 and time1(time2-time1) and filed it into Diff_Time. When any one or two field (time1 or time2) is update, the trigger should update the record in Diff_Time.
Diff_Time format is: hh:mm:ss
I hope anybody can help me on how to create the trigger in sql query.
Thanks

Answer 1

SCOTT@demo102> create table trg_diff (d1 date, d2 date, diff varchar2(8));
Table created.
SCOTT@demo102>
SCOTT@demo102> create or replace trigger trg_diff_bui
  2  before insert or update on trg_diff
  3  for each row
  4  begin
  5   if :new.d1 is not null and :new.d2 is not null then
  6      :new.diff:=(trunc(:new.d2-:new.d1)*24)+to_char(trunc(sysdate)+(:new.d2-:new.d1),'HH24')||':'||to_char(trunc(sysdate)+(:new.d2-:new.d1),'MI:SS');
  7   else
  8      :new.diff:=null;
  9   end if;
10  end;
11  /
Trigger created.
SCOTT@demo102>
SCOTT@demo102> show err
No errors.
SCOTT@demo102>
SCOTT@demo102> insert into trg_diff (d1,d2) values ((sysdate-1.52),sysdate);
1 row created.
SCOTT@demo102> insert into trg_diff (d1,d2) values ((sysdate-2.1),sysdate);
1 row created.
SCOTT@demo102>
SCOTT@demo102> select * from trg_diff;
D1                  D2                  DIFF
22/09/2006 04:26:54 23/09/2006 16:55:42 36:28:48
21/09/2006 14:31:42 23/09/2006 16:55:42 50:24:00
SCOTT@demo102>
SCOTT@demo102> update trg_diff set d1=d1-1;
2 rows updated.
SCOTT@demo102>
SCOTT@demo102> select * from trg_diff;
D1                  D2                  DIFF
21/09/2006 04:26:54 23/09/2006 16:55:42 60:28:48
20/09/2006 14:31:42 23/09/2006 16:55:42 74:24:00
SCOTT@demo102> Do care with length of column diff, in case of hours greater than 99...
Nicolas.