Equivalence of Relational Algebra and Relational Calculus Query Languages Having Aggregate Functions

Abstract

Aggregate functtons m relattonal query languages allow intricate reports to be written. In this paper aggregate functions are precisely defined The definition does not use the notion of “duphcates.” gelattonal algebra and relattonal calculus are extended m a general and natural fashton to include aggregate functions It is shown that the languages so extended have eqmvalent expressive power. © 1982, ACM. All rights reserved.