Transforming UML Class Diagrams into Relational Data Models

Abstract

The Entity-Relationship (ER) method is the most popular method for relational database design. On the other hand, the Unified Modeling Language (UML) is widely used in object- oriented analysis and design. Despite the increasing use of object-oriented techniques for software design and development, there is a large installed base of relational databases. Additionally, object-oriented databases are still not in widespread use. Thus, software designers and developers often turn to the relational databases to make their application objects persistent. Considering the fundamental differences between the two methods, the transformation from UML to a relational data model could be a non-trivial task. The purpose of this chapter is to describe a process that can be used to map a UML class diagram into an ER diagram, and to discuss the potential of using the UML notation to draw ER diagrams. An example of an actual systems design is used throughout to illustrate the mapping process, the associated problems encountered, and how they could be resolved.