A method for detecting intrusion in a database, managed by an access control system, includes defining at least one intrusion detection profile and associating each user with one of said profiles. Each profile includes at least one item access rate. Further, the method determines whether a result of a query exceeds any one of the item access rates defined in the profile associated with the user. In such a case, the access control system is notified to alter the user authorization, thereby making the received request an unauthorized request, before the result is transmitted to the user. Such a method allows for a real time prevention of intrusion by letting the intrusion detection process interact directly with the access control system, and change the user authority dynamically as a result of the detected intrusion.