Inclusion dependencies in database design

A design methodology for relational databases is developed. The main aspects of the methodology are the following. (a) It uses functional dependencies and inclusion dependencies. The latter are essential to model properly e.g. isa-relationships. (b) It is incremental: the database scheme evolves step by step as new information is considered. (c) It is based on an interaction between the designer and a tool that implements the methodology. The basis of the methodology is a normal form for schemes with functional dependencies and inclusion dependencies. Transformations for incrementally changing a scheme into normal form are given.