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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 is represented in terms of tuples, grouped into relations.
Edgar Frank "Ted" Codd (19 August 1923 – 18 April 2003) was an English computer scientist who, while working for IBM, invented the relational model for database management, the theoretical basis for relational databases and relational database management systems.
Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).
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.
A relational database (RDB [1]) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. [ 2 ] A database management system used to maintain relational databases is a relational database management system ( RDBMS ).
Relational developmental systems (RDS) is a developmental psychological metatheory and conceptual framework. [1] It is an extension of developmental systems theory that is based on the view that relationism is a superior alternative to Cartesian mechanism .
Logicians sometimes refer to structures as "interpretations", [2] whereas the term "interpretation" generally has a different (although related) meaning in model theory, see interpretation (model theory). In database theory, structures with no functions are studied as models for relational databases, in the form of relational models.