ERL: Logic for entity-relationship databases |
| |
Authors: | John Grant Tok Wang Ling Mong Li Lee |
| |
Affiliation: | (1) Computer and Information Sciences Department, Towson State University, 21204 Towson, MD;(2) Department of Information Systems and Computer Science, National University of Singapore, 0511 Kent Ridge, Singapore |
| |
Abstract: | We develop a logic for entity-relationship databases, ERL, that is a generalization of database logic. ERL provides advantages to the ER model much as FOL (first-order logic) does to the relational model: a uniform language for expressing database schema, integrity constraints, and database manipulation; clearly defined semantics; the capability to express database transformations; and deductive capabilities. We propose three query languages for ER databases called ERRC, ERSQL, and ERQBE, which are generalizations of the relational calculus, SQL, and QBE, respectively. We use example queries and updates to demonstrate the capabilities of these languages. We apply database transformations to introduce the notion of views and to show that both ERRC and ERSQL are relationally complete.Research sponsored in part by the National Science Foundation under grant IRI-8921951 and by Towson State University. |
| |
Keywords: | entity-relationship model first-order logic entity-relationship logic database language database transformation |
本文献已被 SpringerLink 等数据库收录! |
|