relational expression

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• 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 operator — In computer science, a relational operator is a programming language construct or operator that tests or defines some kind of relation between two entities. These include numerical equality (e.g., 5 = 5) and inequalities (e.g.,… …   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

• 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

• IBM Peterlee Relational Test Vehicle (PRTV) — PRTV ( Peterlee Relational Test Vehicle ) was the world s first relational database management system that could handle significant data volumes. It was a relational query system with powerful query facilities, but very limited update facility… …   Wikipedia

• Tuple relational calculus — The tuple calculus is a calculus that was introduced by Edgar F. Codd as part of the relational model in order to give a declarative database query language for this data model. It formed the inspiration for the database query languages QUEL and… …   Wikipedia

• Comparison of relational database management systems — Programming language comparisons General comparison Basic syntax Basic instructions Arrays Associative arrays String operations …   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

• Common table expression — A Common Table Expression, or CTE, (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement. CTEs can be thought of as alternatives to derived… …   Wikipedia

• Dataphor — is an open source truly relational database management system (RDBMS) and its accompanying user interface technologies, which together are designed to provide highly declarative software application development. The Dataphor Server is a virtual,… …   Wikipedia

• Internet censorship — is control or suppression of the publishing or accessing of information on the Internet. The legal issues are similar to offline censorship.One difference is that national borders are more permeable online: residents of a country that bans… …   Wikipedia