How to detect the change of a table?

I want to know how to detect a change of a table. The TIMESTAMP of it in USER_OBJECTS only tells me a change when the table has more or less columns. I also want to know whether the rows in the table are added/dropped, which select count(*) would work. But I also want to be notified when any update is done on it (say, "John" in column "FIRST_NAME" is changed to "Jones"). How can I do that? Thanks.

This is used in my midnight cron job that queries the table to see if there's a change in it. If anybody likes to have the code of my script, I can email you.

Yong Huang
Email:yong_at_shell.com Received on Wed Jul 22 1998 - 11:34:57 CDT