Baw-Jhiune Liu, Bang-Whang Liu+, Jorng-Tzong Horng#
Department of Electrical Engineering
National Central University,
Chungli, Taiwan, R. O. C.
+Department of Electrical Engineering
#Department of Computer Science & Information Engineering
National Taiwan University
Taipei, Taiwan, R.O.C.
In this paper we address the problem of providing different ways to see objects in an object-oriented database system. The paper first issues the notions of "derived object", "virtual object", and "virtual schema", and then provides a mechanism to construct user-specific views that simply and naturally extends the underlying object-oriented data model. The user view is constructed by operators defined in this paper, which are powerful enough to capture the essential feature of data abstraction and inheritance in the underlying data model. The method of mapping from the view to the conceptual model is presented by examples.
Keywords: object-oriented model, semantic data model, view, derived object
Received April 16, 1990; revised November 16, 1990.
Communicated by Y. S. Kuo.
*This work was partially supported by the National Science Council under grant NSC78-0408-E008-04.