active record and errors

[eluser]akkumaru[/eluser]
Hi, all,,
I want to know How to catch all kind of possible errors when i'm using Active Record,,

e.g.
How do I know an insertion or update is failed so that I can set up an error handling strategy?
Or How do I know a database error occures while prevent the CI error message to be written to the page, so that I can set up my error handling strategy?

I've tried the try{}catch(Exception $e){} clause,, but it seems it didn't work,,