D (data language specification)
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D is a set of requirements proposed by Christopher J. Date and Hugh Darwen in their book The Third Manifesto for what they believe a relational database query language ought to be like; D is not a language itself.
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[edit] Overview
D, by itself, refers to a set of requirements proposed by Date and Darwen for what they believe a relational language ought to be like. Tutorial D is an abstract instantiation of D which is described and used in The Third Manifesto. It should be noted that it is not required for instantiations of D to have the same syntax as Tutorial D; just that 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 databases.
[edit] Tutorial D
Tutorial D is an abstract instantiation of D, described and used in The Third Manifesto. The purpose of Tutorial D is to show what a D might be like. Its purpose is educational.
[edit] Industrial D
While Tutorial D is an academic language, any relatively faithful implementation of D meant to be used in the industry is called an Industrial D.
[edit] Implementations
D’s first implementation is D4, written in C#. D4 is the flagship language of Alphora's Dataphor. Others include Rel, Opus, Duro and Dee. All would be considered "Industrial D"s even though Rel calls their language "Tutorial D".
[edit] References
[edit] Further reading
- Foundations for Future Databases: The Third Manifesto by Christopher J. Date and Hugh Darwen, 1998.
- SQL Alternatives
