This paper demonstrates that a simple rule system can be constructed that supports a more powerful view system than available in current commercial systems. Not only can views be specified by using rules but also special semantics for resolving ambiguous view updates are simply additional rules. Moreover, procedural data types as proposed in POSTGRES are also efficiently simulated by the same rules system. Lastly, caching of the action part of certain rules is a possible performance enhancement and can be applied to materialize views as well as to cache procedural data items. Hence, we conclude that a rule system is a fundamental concept in a next generation DBMS, and it subsumes both views and procedures as special cases.