Relational calculus consist of two calculi, the tuple relational calculus and the domain relational calculus, that are part of the relational model for databases and provide a declarative way to specify database queries. The Tuple Calculus is a calculus that was introduced by Edgar F In Computer science, domain relational calculus ( DRC) is a calculus that was introduced by Michel Lacroix and Alain Pirotte as a declarative The relational model for Database management is a Database model based on first-order predicate logic, first formulated and proposed in 1969 by Edgar This in contrast to the relational algebra which is also part of the relational model but provides a more procedural way for specifying queries. Relational algebra, an offshoot of First-order logic (and of Algebra of sets) deals with a set of relations closed under Operators

The relational algebra might suggest these steps to retrieve the phone numbers and names of book stores that supply Some Sample Book:

1. Join books and titles over the BookstoreID.
2. Restrict the result of that join to tuples for the book Some Sample Book.
3. Project the result of that restriction over StoreName and StorePhone.

The relational calculus would formulate a descriptive, declarative way:

Get StoreName and StorePhone for supplies such that there exists a title BK with the same BookstoreID value and with a BookTitle value of Some Sample Book.

The relational algebra and the relational calculus are logically equivalent: for any algebraic expression, there is an equivalent expression in the calculus, and vice versa.

References

• Date, Christopher J. (2004). Chris Date (born 1941 is an independent author lecturer researcher and consultant specializing in relational database technology An Introduction to Database Systems, 8th, Addison Wesley. ISBN 0-321-19784-4.  

See also

• The Third Manifesto
• Tutorial D
• D (data language specification)
• D4 (programming language) (an implementation of D)
• Aldat Relational Algebra

The Third Manifesto ( 1995) is Christopher J Date 's and Hugh Darwen 's proposal for future Relational database management systems that would avoid 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 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 D4 is a Computer language used in Dataphor, a truly Relational Database Management System.

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