Conceptual Modelling of Database Applications Using an Extended Er Model

In this paper, we motivate and present a data model for conceptual design of structural and behavioural aspects of databases. We follow an object centered design paradigm in the spirit of semantic data models. The speciication of structural aspects is divided into modelling of object structures and modelling of data types used for describing object properties. The speciication of object structures is based on an Extended Entity{Relationship (EER) model. The speciication of behavioural aspects is divided into the modelling of admissible database state evolutions by means of temporal integrity constraints and the formulation of database (trans)actions. The central link for integrating these design components is a descriptive logic{ based query language for the EER model. The logic part of this language is the basis for static constraints and descriptive action speciications by means of pre-and postconditions. A temporal extension of this logic is the speciication language for temporal integrity constraints. We emphasize that the various aspects of a database application are speciied using several appropriate , but yet compatible formalisms, which are integrated by a unifying common semantic. Contents Abstract 1 1 Introduction 1