By Carol Batini;Stefano Ceri;Shamkant B. Navathe
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Extra info for Conceptual Database Design: An Entity-Relationship Approach
WIEDERHOLD. Database Design. 2d ed. McGraw-Hill, 1984. G. viEDERHOLD. Database Design for File Organizations. McGraw-Hill, 1987. These books concern the area ofdatabase design. HOWE (1983) addresses mainly conceptual and logical design, while TEOREY and FRY (1982) and WIEDERHOLD (1984) extensively address the area of physical design. WIEDERHOLD (1987) presents a variety of techniques for the design of file-system organizations. LOOMIS (1987) uses a semantic data modeling technique and shows how conceptual models can serve as basis for designing relational, hierarchical, and network databases.
13 describes a reality in which persons own cars; it includes three records (PERSON, OWNS, CAR) and seven fields (NAME, SEX, ADDRESS, SOCIAL-SECURITY-NUMBER, PLATE, MAKE, COLOR). The sample schema corresponds to two classes, modeled by record types PERSON and CAR, and a binary aggregation of the two classes, modeled by record type oWNs. An instance of a schema is a dynamic, time-variant collection of data that conforms to the structure of data defined by the schema. Each schema can have multiple instances; the state of the database at a particular point of time corresponds to one such instance.
In this book, we have emphasized data processing application, and from this context the dataflow model has emerged, becoming an industry standard. This model is simple and concise; furthermore, each element of the model is mapped to a distinct graphic symbol. More recently, the focus has moved from data models to design methodologies and tools; one may argue that a correct methodological approach is at least as important as the choice of data or function models. Further, a variety of computer-based design tools have been developed, many of which support a graphic representation of data and function schemas.