Notify / Check if database content has changed

Is it possible to know when and if the contents of certain tables in a databa开发者_Go百科se has changed? I' builting an multiuser app, and I want to notify the user if somebody else modified any relevant data. I'm using an Oracle 10g database and an .NET WinForms app.

Thanks!

---

One approach is that each time you make an update to the users data you increment a counter associated with that user. Then your application can grab that counter from time to time and see if it has increased and so know if it needs to update itself because something has changed. This is easy to implement.

I am sure Oracle has some callback mechanism that allows it to tell you when an update has occured. This would be more efficient but I do not know enough about Oracle to provide more information about that approach.