A variable that contains a relation, as distinguished from the relation itself.

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  • relvar — |è| v. tr. 1. Cobrir de relva. • v. intr. 2. Relvejar …   Dicionário da Língua Portuguesa

  • relvar — (Del lat. relevāre). tr. Levantar el barbecho …   Diccionario de la lengua española

  • Relvar — In relational databases, a relvar is a term coined by C. J. Date as an abbreviation for the concept of relation variable , which is the actual term used by the inventor of R/M E. F. Codd regarding the same concept, and is not universally accepted …   Wikipedia

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  • 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

  • Candidate key — In the relational model, a candidate key of a relvar (relation variable) is a set of attributes of that relvar such that # at all times it holds in the relation assigned to that variable that there are no two distinct tuples with the same values… …   Wikipedia

  • Superkey — A superkey is defined in the relational model of database organization as a set of attributes of a relation variable (relvar) for which it holds that in all relations assigned to that variable there are no two distinct tuples (rows) that have the …   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

  • 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

  • Row (database) — In the context of a relational database, a row also called a record or tuple represents a single, implicitly structured data item in a table. In simple terms, a database table can be thought of as consisting of rows and columns or fields. Each… …   Wikipedia

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