Track last operation on particullar row(identified by primary key)

Question

I have two table 'EMP' and EMP_CLASS ,There is a store procedure which is execute in every ten minutes interval.
Role of procedure is to take back up from emp table only changes affeted to the rows in between that 10 minutes.
But i want something like this suppose there is a row inserted once and updated once within that interval,
I want only last transaction should be taken to consideration by the procedure of same row.
can anyone please tell me how to achive this?

Answer 1

Hi,
1) If you have the right to alter the table emp, you can add a column that flag the new/modified rows:
alter table emp add(flg_modified varchar2(1) default 'Y')
create or replace trigger flag_changed_rows
before update
on emp
referencing new as new old as old
for each row
begin
   :new.flg_modified   := 'Y';
end;
/.. and in your procedure backup only changed/new rows in the emp_class table.
insert into EMP_CLASS(...)   /* All columns exception the flg_modified column */
select (...)  from emp where flg_modified = 'Y';
update emp
set flg_modified = 'N'
where flg_modified = 'Y';
commit;2) if you don't have the right to add a column in the emp table, you can use a merge statement in the backup procedure:
(pseudo code):
merge into emp_class ec using
(select * from emp) e
on(e.pk=ec.pk) /*put an unique id*/
when matched then update set ..
where /* test if the fields are different */
when no matched then insert
/* insert the record here */
... REM: this solution will force you to read the full content of you EMP table . (can be 'problematic' if the table is huge).
3) or use a flahback query and compare the DELTA (but you need to be precautious to define the single point in time between subsequent executions)
Edited by: user11268895 on Aug 16, 2010 11:56 AM
Edited by: user11268895 on Aug 16, 2010 11:57 AM