Technical Report CS0392

Title: Entity-Relationship Consistency for Relational Schemas
Authors: J. Makowsky, V.M. Markowitz and N. Rotics
Abstract: We investigate the significance of requiring from a relational database schema to comply with an entity-relationship structure. Relational database schemas here consist of a traditional relational schema together with key and inclusion dependencies. Such a schema is said to be entity-relationship (ER) consistent, if it is possible to translate it into an entity-relationship schema. An algorithm is presented which decides if a schema is ER-consistent and its complexity is discussed. ER-consistency allow us to carryover precisely all the advantages of the ER-oriented design principles to the relational model and makes possible the direct use of ER oriented query and update languages within the relational model. ER-consistency carries out on a higher level the data independence objective of the relational model by making independent the information structure from its logical data representation. Moreover, ER-consistency expresses information structure normalization just as relational normal forms represent data representation normalization. We propose an Entity-Relationship Normal Form for ER-consistent relational schemas and present the corresponding normalization procedure.
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