Located at http://dataphor.org, a modern implementation of a faithful RelationalLanguage.  

''[Actually, there are a number of them.  See RelationalLanguage and TutorialDee.]''  

Not yet a standalone RDBMS, though.

It is a Virtual RDBMS incorporating a develpment framework.  It sits between users and SQL DBMSs, hiding SQL ugliness and relational violations away and presenting a clean relational language and a RAD environment.

There are only two languages, D4 which is Pascal-flavoured and RealSQL for SQL familiarity.

It is quite simple.  One defines the data model and integrity constraints, interfaces and business rules are derived.  Sticking to the RelationalModel and good language design principles makes it much simpler than current alternatives.

It doesn't implement HughDarwen's and ChrisDate's hierarchical type system, but it does have user-defined types.

-- LeandroDutra

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''Is AlphoraDataphor really 100 percent faithful or just aiming to be pretty close? ''

Should someone invite the authors (Alphora) of Dataphor to participate in Wiki an clarify their intentions? Or would that be wrong because they would provide us with a biased "our product is perfect and everything else sucks" perspective? --LuxSpes

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See DataphorIsOpenSource