The semantic data model
Michael M. Hammer, Dennis J. McLeod · 1978
Conventional data models are not satisfactory for modelling data base application systems. The features that they provide are too low level and representational to allow the semantics of a data base to be directly expressed in the schema. The semantic data model (SDM) has been designed as a natural application modelling mechanism that can capture and express the structure of an application environment. The features of the SDM correspond to the principal intensional structures naturally occurring in contemporary data base applications. Furthermore, facilities for expressing derived (redundant) information are an essential part of the SDM; derived information is as prominent in an SDM schema as is primitive data. The SDM is designed to enhance the effectiveness and usability of computerized data bases. It can serve as a formal specification and documentation mechanism for a data base, can support a variety of powerful user interface facilities, and can be used as a tool in the data base design process.