The Nested Entity-Relationship Model

Abstract

The primary goal of this dissertation is to propose a new approach to modelling large and complicated database objects. The Nested Entity-Relationship (NER) model is proposed as an improvement for the flat semantic models in order to overcome the comprehension and the layout problem exhibited by them. The third dimension is utilized by the NER model in the development of both complex entity types and complex relationship types. As a design tool, the NER model provides a top down approach to the refinement of object structures and semantic connections. As a logical description of an existing database, the NER model can be automatically generated based on the relational schema and inclusion dependencies. The NER model is theoretically sound in the sense that each complex object type is supportable in terms of its structural properties. This is shown based on the theory of the complex relational views defined in this dissertation. In addition, each object is semantically consistent if it conforms the semantic constraints.