Inclusion Dependencies

Inclusion Dependencies

Laura C. Rivero (Universidad Nacional del Centro de la Provincia de Buenos Aires, Argentina), Jorge H. Doorn (Universidad Nacional de la Plata, Argentina) and Viviana E. Ferraggine (Universidad Nacional del Centro de la Provincia de Buenos Aires, Argentina)
DOI: 10.4018/978-1-878289-88-9.ch011


The evaluation of conceptual schemes of actual databases may result in the discovery of inclusion dependencies. An inclusion dependency is defined as the existence of attributes in a table whose values must be a subset of the values of attributes in another table. When the latter set conforms a key for its table, the inclusion dependency is key-based. Key-based inclusion dependencies are fully enforced by most current database systems. On the contrary, if the second set is not the key of the relation, the inclusion dependency is non-key-based. This kind of inclusion dependency is completely disregarded by actual systems, obliging the users to manage them via special-case code or triggers. This implies an excessive effort to maintain integrity and develop applications, among other inconveniences. The chapter goal is to give a heuristics to redesign the conceptual schema. This is based on the identification of hidden business rules and the conversion of non-key inclusion dependencies into key-based ones.

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