How to find last updated record of a table?

Hi...

I am Using Oracle 10g XE.

I want to find last updated record of a table. Table name is 'DUP';


I wrote a trigger as follows....
>>

SQL> CREATE OR REPLACE TRIGGER LUR
2 BEFORE UPDATE OR INSERT
3 ON DUP FOR EACH ROW
5 BEGIN
6 SELECT SYSTIMESTAMP INTO :NEW.N_TS FROM DUAL;
7 END;
8 /

<<

I am getting PLS-00049.

If this trigger works properly, i can find last updated record as......

>>

SQL> SELECT * FROM DUP WHERE N_TS =(SELECT MAX(N_TS) FROM DUP);

<<

can anyone help me here....

Thanks & Regards

Raj S Vaida

Describe the table DUP