The Relational Data Model

Abstract

Database technology has been evolving so rapidly and fruitfully since late 50’s, motivated by the demands for storing large-scale data, facilitating data-sharing, minimizing data redundancy, upgrading data independency, guaranteeing data consistency and integrity, etc. Due to the key role in data management played by database systems, the fields of database application and research nowadays continue to broaden and deepen enormously. It is hard to imagine the effectiveness of any modern system without a proper data management functionality. Usually, database systems developed are based upon certain data models. As already known (see Date, 1986; Ullman, 1982, 1988; Pratt and Adamski, 1987; Elmasri and Navathe, 1994; etc.), there have been, for example, the hierarchical model, the network model, the relational model, and the object-oriented model. The following discussions, however, will center around the relational model. The reason, among others, is its popularity owing to its rigorousness in theory, fundamentalness in modeling and usefulness in practice.