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  2. Relational calculus - Wikipedia

    en.wikipedia.org/wiki/Relational_calculus

    The relational calculus is similar to the relational algebra, which is also part of the relational model: While the relational calculus is meant as a declarative language that prescribes no execution order on the subexpressions of a relational calculus expression, the relational algebra is meant as an imperative language: the sub-expressions of ...

  3. Codd's theorem - Wikipedia

    en.wikipedia.org/wiki/Codd's_theorem

    Codd's theorem states that relational algebra and the domain-independent relational calculus queries, two well-known foundational query languages for the relational model, are precisely equivalent in expressive power. That is, a database query can be formulated in one language if and only if it can be expressed in the other.

  4. Domain relational calculus - Wikipedia

    en.wikipedia.org/wiki/Domain_relational_calculus

    In computer science, domain relational calculus (DRC) is a calculus that was introduced by Michel Lacroix and Alain Pirotte as a declarative database query language for the relational data model. [ 1 ]

  5. Tuple relational calculus - Wikipedia

    en.wikipedia.org/wiki/Tuple_relational_calculus

    Since the calculus is a query language for relational databases we first have to define a relational database. The basic relational building block is the domain (somewhat similar, but not equal to, a data type). A tuple is a finite sequence of attributes, which are ordered pairs of domains and values. A relation is a set of (compatible) tuples ...

  6. Relation (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Relation_(mathematics)

    Modelling of Concurrent Systems: Structural and Semantical Methods in the High Level Petri Net Calculus. Herbert Utz Verlag. ISBN 978-3-89675-629-9. Rosenstein, Joseph G. (1982), Linear orderings, Academic Press, ISBN 0-12-597680-1; Schmidt, Gunther (2010). Relational Mathematics. Cambridge: Cambridge University Press. ISBN 978-0-521-76268-7.

  7. Category:Relational model - Wikipedia

    en.wikipedia.org/wiki/Category:Relational_model

    This page was last edited on 11 February 2014, at 21:35 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.

  8. Conjunctive query - Wikipedia

    en.wikipedia.org/wiki/Conjunctive_Query

    Conjunctive queries without distinguished variables are called boolean conjunctive queries.Conjunctive queries where all variables are distinguished (and no variables are bound) are called equi-join queries, [1] because they are the equivalent, in the relational calculus, of the equi-join queries in the relational algebra (when selecting all columns of the result).

  9. Relation algebra - Wikipedia

    en.wikipedia.org/wiki/Relation_algebra

    In mathematics and abstract algebra, a relation algebra is a residuated Boolean algebra expanded with an involution called converse, a unary operation.The motivating example of a relation algebra is the algebra 2 X 2 of all binary relations on a set X, that is, subsets of the cartesian square X 2, with R•S interpreted as the usual composition of binary relations R and S, and with the ...