The MR Diagram - A Model for Conceptual Database Design

Traditional database models are not sufficiently expressive for a variety of standard and non-standard database applications. Several models supporting greater abstraction have been proposed to 611 this gap, but no one model has gained wide acceptance. This paper delnes a model, based on the notion of molecules and non-jirat normal /arm relations, that provides a powerful abstraction mechanism using aggregation. The model also provides a simple pictorial representation that allows a compact and clear specitlcation of a database. We illustrate the model with several examples and show how it can be used in the design of databases.