Schema Integration and View Derivation by Resolving Intensional andExtensional

The integration of schemata is a very essential but also a very complex task in a federated database environment. Especially the integration of diierent inheritance hierarchies into one hierarchy is not satisfactorily solved up to now. We show, why some existing approaches fail and propose a new algorithm, which further meets the demand for complete, correct and minimal integrated schemata. Furthermore, with respect to the well-known concept of logical data independence , our algorithm supports the derivation of diierent view-dependent external schemata. External object-oriented schemata can be automatically generated by our algorithm. Our approach can be applied to scenarios diierent from the integration problem, e.g. for schema evolution , views in object-oriented database systems, and classiication problems.