Automatic database logging

[eluser]Unknown[/eluser]
Hi there,
i got a CI application in which i got many and many database insert, update, delete calls.
Now i want to establish a "user log database table", in which all actions of all users should be automatically logged, including:
- create a record
- delete a record
- update a record, and here: which field is updated - what are its old and new values?
- maybe anything more

I wonder, if there is a smart and easy CI way of doing this. Maybe there is an existing function or a library.
Or do i have to write an own library with hooks before DB calls?

I really do not know, where to start.
The most important thing is, that the log funtionality is in only one global method, which, in best case, writes those logs automatically based on the last database action(s).

Best regards,
forTeesSake