Semantic aspects of data dependencies and their application to relational database design
Yumi Kambayashi, Katsumi Tanaka, Shuzo Yajima · 2005
In this paper, we mainly discuss the semantic aspects of functional and multivalued dependencies in order to choose a better logical design of a relational database. We clarify the differences between a conceptual design and a logical design of a relational database. For example, a multivalued dependency does not always capture a conceptual dependency such that a data element semantically determines a set of other data elements. Moreover, some transitively specified multivalued dependencies are shown to often impose a semantically unnatural constraint. A sufficient condition for these multivalued dependencies to hold in a natural sense is provided. A mixed design approach of a conceptual and a logical designs is introduced, in which each design approach is compensated for its deficiency by the other one. Some generalization of a relational model is also suggested to handle some interface problems between a logical design and a conceptual design, such as a null value problem and an entity identification problem.