Temporal Databases

Abstract

In this chapter, the reader is acquainted with the basic concepts of temporal databases, i.e. databases that deal explicitly with time-related concepts and information. Examples of clinical data with valid and transaction times are given. A classification of temporal databases according to the supported temporal dimensions is presented. The reader, then, learns how the relational model and the related algebra, calculus, and query languages have been extended to deal with the di_erent time aspects. The presentation then focuses on the main data models employed in the conceptual design, the Entity-Relationship data model and the Object-Oriented data models. The reader learns how to design a temporal database schema by both the standard (atemporal) data models and their corresponding temporally-oriented extensions. Finally, the reader is guided through some basic features of object-oriented query languages and their extensions for temporal information. A section on further topics related to temporal databases sketches some research directions on multimedia and semistructured temporal data.