Two-dimensional specification of queries in object-oriented databases |
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| Institution: | 1. Display Device Group, Image Media Lab., LG Electronics nc., 16, WooMyeon, Seocho, Seoul 137-140, South Korea;2. Department of Information and Communications Engineering, KAIST, 207-43, Cheongryang, Dongdaemun, Seoul 130-012, South Korea;1. ICPEES – Institut de Chimie et Procédés pour l’Energie, l’Environnement et la Santé, Group of Atmospheric Physical Chemistry, UMR 7515 CNRS – Université de Strasbourg – ECPM, 25 rue Becquerel, F-67087, Strasbourg Cedex 2, France;2. ICPEES – Institut de Chimie et Procédés pour l’Energie, l’Environnement et la Santé, Group of Energy and Fuels for a Sustainable Environment, UMR 7515 CNRS – Université de Strasbourg – ECPM, 25 rue Becquerel, F-67087, Strasbourg Cedex 2, France;3. CMC – Chemistry of Complex Matter – Laboratory of Molecular Tectonics, UMR 7140 CNRS, Université de Strasbourg, 4 rue Blaise Pascal, F-67000, Strasbourg, France |
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| Abstract: | Visual queries based on schema graphs simplify access to databases for technical and non-technical users. Unlike relational databases, in object-oriented databases, the basic entity in a query, i.e. a class, is frequently considered as a compound of several entities to which the query operations may apply, which causes the deficiency in describing an entity of designation. In this paper, we propose a visual query language object query diagram (OQD) for object-oriented databases, where a class is decomposed into a number of object sets, each of which is a set of values of one of the attributes of the other classes. By representing each class and object sets in the class using the well-known Venn diagram in a query, OQD explicitly presents all the entities to which the operations in a query can apply. We describe the syntax and semantics of OQD through a number of illustrative examples. |
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