Relational schemas consisting of relation-schemes, key dependencies and key-based inclusion dependencies (referential integrity constraints) are considered. Schemas of this form are said to be entity-relationship (EER)-convertible if they can be associated with an EER schema. A procedure that determines whether a relational schema is EER-convertible is developed. A normal form is proposed for relational schemas representing EER object structures. For EER-convertible relational schemas, the corresponding normalization procedure is presented. The procedures can be used for analyzing the semantics of existing relational databases and for converting relational database schemas into object-oriented database schemas. >
['Victor Markowitz', 'Johann A. Makowsky']
Identifying extended entity-relationship object structures in relational schemas