Integration of Derived Classes in Object Schemas
نویسندگان
چکیده
In the definition of derived classes in OODBs, the problem of integration of derived classes in object schemas is one of the main issues that has to be resolved. Derived classes are defined during the lifetime of the database to be included in some external schema or in the conceptual schema. Different solutions to this problem have been previously proposed; some of them involve the extension of the object-orientation paradigm to include new kinds of relationships. In this paper, a new solution according to the ANSI/SPARC framework is put forward. Derived classes are integrated in two phases: first, in the data dictionary using the derivation relationship; then, in the conceptual schema or external schemas using the inheritance relationship. The derivation relationship only appears in the data dictionary, therefore, in this solution the objectorientation paradigm is not extended.
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