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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.
The dimensional model is a specialized adaptation of the relational model used to represent data in data warehouses in a way that data can be easily summarized using online analytical processing, or OLAP queries. In the dimensional model, a database schema consists of a single large table of facts that are described using dimensions and measures.
[2] [3] [4] The MICRO Relational Database Management System which was implemented in 1970 was based on Childs' Set-Theoretic Data Structure (STDS) work. [citation needed] In 1970 Codd in his key paper on relational databases, A Relational Model of Data for Large Shared Data Banks, cited one of Childs' 1968 papers as part of the basis for the ...
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).
Edgar F. Codd released his original article "A Relational Model of Data for Large Shared Databanks" in June 1970. This was the first time the notion of a relational database was published. All work after this, including the Boyce–Codd normal form method was based on this relational model.
Codd introduced the term relational in his research paper "A Relational Model of Data for Large Shared Data Banks". [2] In this paper and later papers, he defined what he meant by relation. One well-known definition of what constitutes a relational database system is composed of Codd's 12 rules.
[5] [6] A relational database definition (database schema, sometimes referred to as a relational schema) can thus be thought of as a collection of named relation schemas. [7] [8] In implementations, the domain of each attribute is effectively a data type [9] and a named relation schema is effectively a relation variable (relvar for short).
Relational database – collection of data items organized as a set of formally described tables from which data can be accessed easily. Relational database management system (RDBMS) – database management system (DBMS) that is based on the relational model as introduced by E. Relational model – for database management is a database model ...