An object-oriented approach to a temporal query language

Abstract

Time constraints and the temporal dimension are an essential aspect in many real world systems, like cooperative work and industrial production systems. Traditional database systems support these features only through application programs. The recent tendency consists of representing the temporal aspects in the database schema and in the corresponding query language and supporting them directly in the DBMS. In this paper the different aspects of adding the temporal dimension m an object-oriented data model are analyzed and a classification scheme is proposed for the types of possible queries. Based on this classification, a query language for the object-oriented TI"-ORM data model is presented and discussed in detail. In TF-ORM. both transaction and valid times are associated to data and the query language is used to retrieve information about the database current valid information, about past valid values, and about past histories.