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The four relational models are as follows: Communal sharing (CS) relationships are the most basic form of relationship where some bounded group of people are conceived as equivalent, undifferentiated and interchangeable such that distinct individual identities are disregarded and commonalities are emphasized, with intimate and kinship relations being prototypical examples of CS relationship. [2]
The relational model (RM) is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, [1] [2] where all data are represented in terms of tuples, grouped into relations.
Codd continued to develop and extend his relational model, sometimes in collaboration with Christopher J. Date. [24] One of the normalised forms, the Boyce–Codd normal form, is named after him. [25] Codd's theorem, a result proven in his seminal work on the relational model, equates the expressive power of relational algebra and relational ...
Database theory encapsulates a broad range of topics related to the study and research of the theoretical realm of databases and database management systems.. Theoretical aspects of data management include, among other areas, the foundations of query languages, computational complexity and expressive power of queries, finite model theory, database design theory, dependency theory, foundations ...
Codd's theorem states that relational algebra and the domain-independent relational calculus queries, two well-known foundational query languages for the relational model, are precisely equivalent in expressive power. That is, a database query can be formulated in one language if and only if it can be expressed in the other.
Knapp's relational development model portrays relationship development as a ten step process, broken into two phases. Created by and named after communication scholar Mark L. Knapp , the model suggests that all of the steps should be done one at a time, in sequence, to make sure they are effective.
From 1978 to 1982 he was a chief architect on Business System 12, a database management system that faithfully embraced the principles of the relational model. [3] He worked closely with Christopher J. Date and represented IBM at the ISO SQL committees (JTC1 SC32 WG3 Database languages, [4] WG4 SQL/MM [5]) until his retirement from IBM.
The Database Relational Model: A Retrospective Review and Analysis, 2001, ISBN 0-201-61294-1; Temporal Data & the Relational Model, 2003, ISBN 1-55860-855-9; An Introduction to Database Systems, 2004, ISBN 0-321-19784-4; Database in Depth: Relational Theory for Practitioners, 2005, ISBN 0-596-10012-4