Issue No.01 - January (1981 vol.7)
S. Al-Fedaghi , Department of Electrical Engineering and Computer Science, Northwestern University
The typical design process for the relational database model develops the conceptual schema and each of the external schemas separately and independently from each other. This paper proposes a new design methodology that constructs the conceptual schema in such a way that overlappings among external schemas are reflected. If the overlappings of external schemas do not produce transitivity at the conceptual level, then with our design method, the relations in the external schemas can be realized as a join over independent components. Thus, a one-to-one function can be defined for the mapping between tuples in the external schemas to tuples in the conceptual schema. If transitivity is produced, then we show that no such function is possible and a new technique is introduced to handle this special case.
relational database mode, Conceptual schema, external schema, functional dependencies, independent components, interferences, logical database design, mapping functions
S. Al-Fedaghi, "Mapping Considerations in the Design of Schemas for the Relational Model", IEEE Transactions on Software Engineering, vol.7, no. 1, pp. 99-111, January 1981, doi:10.1109/TSE.1981.234512