Relational algebra

Смотреть что такое "Relational algebra" в других словарях:

• Relational algebra — Not to be confused with Relation algebra. Relational algebra, an offshoot of first order logic (and of algebra of sets), deals with a set of finitary relations (see also relation (database)) that is closed under certain operators. These operators …   Wikipedia

• relational algebra — saryšių algebra statusas T sritis automatika atitikmenys: angl. relational algebra vok. Relationsalgebra, f rus. алгебра отношений, f; реляционная алгебра, f pranc. algèbre des relations, f …   Automatikos terminų žodynas

• Projection (relational algebra) — IntroductionIn relational algebra, a projection is a unary operation written as pi {a 1, ...,a n}( R ) where a 1,...,a n is a set of attribute names. The result of such projection is defined as the set obtained when the components of the tuple R… …   Wikipedia

• Selection (relational algebra) — In relational algebra, a selection (sometimes called a restriction to avoid confusion with SQL s use of SELECT) is a unary operation written assigma {a heta b}( R ) or sigma {a heta v}( R ) where: * a and b are attribute names * heta is a binary… …   Wikipedia

• Rename (relational algebra) — In relational algebra, a rename is a unary operation written as ho {a/b}(R) where:* a and b are attribute names * R is a relationThe result is identical to R except that the b field in all tuples is renamed to an a field. For an example, consider …   Wikipedia

• 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. This in contrast to the relational algebra… …   Wikipedia

• Algebra (disambiguation) — Algebra is a branch of mathematics.Algebra may also mean: * elementary algebra * abstract algebra * linear algebra * universal algebra * computer algebraIn addition, many mathematical objects are known as algebras. * In logic: ** Boolean algebra… …   Wikipedia

• Relational — may refer to: *Relational (mathematics) *Relational aggression *Relational algebra *Relational art *Relational database *Relational calculus *Relational operator *Relational model *Relational theory *Relational philosophy *Relational… …   Wikipedia

• Relational database — A visual diagram showing the relationship between the two tables, as indicated by the arrow A relational database matches data by using common characteristics found within the data set. The resulting groups of data uses the relational model (a… …   Wikipedia

• Relational model — The relational model for database management is a database model based on first order predicate logic, first formulated and proposed in 1969 by Edgar Codd. [ Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks , E.F …   Wikipedia