Affiliation:
1. Graduate School of Business Administration New York University New York, N.Y.
2. Fachbereich Informatik Universität Hamburg Schlüterstr. FRG
Abstract
Database queries explicitly containing existential and universal quantification become increasingly important in a number of areas such as integrity checking, interaction of databases and AI systems, heterogeneous databases, and statistical databases. Using a concept of range nesting in relational calculus expressions, the paper describes evaluation algorithms and transformation methods for an important class of quantified relational calculus queries called perfect expressions. This class includes well-known classes of "easy" queries such as tree queries (with free and existentially quantified variables only), and complacent (disconnected) queries.
Publisher
Association for Computing Machinery (ACM)
Subject
Information Systems,Software
Cited by
5 articles.
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