Publication Date



The derivation rules from an enhanced conceptual structure into a logical schema for network and relational databases are examined. The initial conceptual structure (being itself a derivation from the predefined set of user requirements on data) captures the extended range of semantic modeling constructs, such as: partial and total entities of a relationship, weak and regular relationships, ternary, recursive and nonunivocal relationships, subset and generic relationships. An enhanced conceptual structure is subjected to transforms into logical schemas in a process which is tractable by computer-assisted tools and guarantees to produce feasible network and relational structures.Ten of the basic conceptual structures - from the overall number of one hundred transforms recognizable by the system - are presented with respect to the network database design and then again for the relational database design. The CAD-tool, written in Macintosh Pascal, is briefly described.