D (data language specification) - AbsoluteAstronomy.com

D is a set of requirements for what Christopher J. Date

Christopher J. Date

Chris Date is an independent author, lecturer, researcher, and consultant, specializing in relational database theory.-Biography:Chris Date attended High Wycombe Royal Grammar School from 1951 to 1958 and received his BA in Mathematics from Cambridge University in 1962. He entered the computer...

and Hugh Darwen

Hugh Darwen

Hugh Darwen is a computer scientist who was an employee of IBM United Kingdom from 1967 to 2004, and has been involved in the history of the relational model.- Work :...

believe a relational database

Relational database

A relational database is a database that conforms to relational model theory. The software used in a relational database is called a relational database management system . Colloquial use of the term "relational database" may refer to the RDBMS software, or the relational database itself...

query language

Query language

Query languages are computer languages used to make queries into databases and information systems.Broadly, query languages can be classified according to whether they are database query languages or information retrieval query languages...

ought to be like. It is proposed in their book The Third Manifesto
The Third Manifesto
The Third Manifesto is Christopher J. Date's and Hugh Darwen's proposal for future database management systems, a response to two earlier Manifestos with the same purpose. The theme of the manifestos is how to avoid the 'object-relational impedance mismatch' between object-oriented programming...

.

Overview

D by itself is an abstract language specification. It does not specify language syntax. Instead, it specifies desirable and undesirable language characteristics in terms of prescriptions and proscriptions. Thus, D is not a language but a family of both implemented and future languages. A "valid D" must have a certain set of features, and exclude a different set of features which Date and Darwen consider unwise. A valid D may have additional features which are outside the scope of relational database

Relational database

Tutorial D

Tutorial D is a specific D which is defined and used for illustration in The Third Manifesto. Implementations of D need not have the same syntax as Tutorial D. The purpose of Tutorial D is both educational and to show what a D might be like. Rel

Rel (DBMS)

Rel is an open source true relational database management system that implements a significant portion of Chris Date and Hugh Darwen's Tutorial D query language.Primarily intended for teaching purposes, Rel is written in the Java programming language....

is an implementation of Tutorial D.

Implementations

D’s first implementation is D4

D4 (programming language)

D4 is a computer language used in Dataphor, a relational database management system.-Syntax:Alphora, the creators of D4, have given it a Pascal like syntax...

, written in C#. D4 is the flagship language of Alphora's Dataphor

Dataphor

Dataphor is an open-source truly relational database management system and its accompanying user interface technologies, which together are designed to provide highly declarative software application development...

. Others include Rel

Rel (DBMS)

(see above), Opus, Duro, and Dee.

External links

Tutorial D explained
Tutorial D's grammar in alphabetical order
ALGEBRA, a recursive name that means A Logical Genesis Explains Basic Relational ALGEBRA.
The Third Manifesto
Alphora
Rel - An Implementation of Date and Darwen's Tutorial D database language.
Duro - a relational database management system
Dee - makes Python relational

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