PSQL - A QUERY LANGUAGE FOR PROBABILISTIC RELATIONAL DATA

Database systems based on the relational model have become very popula r for the storage of large volumes of business-related data. Although the relational model provides a great range of advantages over other d ata models, it was designed to support deterministic data and, consequ ently, it lacks a comprehensive way for handling uncertain data. Howev er, in all real-world environments, uncertainty in data values is a co mmon occurrence. Therefore, there is a need to extend the relational m odel so that data uncertainty can be captured explicitly. In an earlie r work, we have proposed a probabilistic relational algebra that is a consistent extension of the conventional relational algebra and is red ucible to the latter. The contribution of this work is the development of a non-procedural probabilistic query language-structured around th e popular SQL-that can be built on top of that algebra. We formalize t he extended syntax, provide examples to illustrate the syntax, and exa mine query formulation from a decision-theoretic perspective (C) 1998 Elsevier Science B.V.