relational query
1relational query — sąryšinė užklausa statusas T sritis informatika apibrėžtis ↑Užklausa gauti susietiems duomenims iš dviejų arba daugiau ↑sąryšinės duomenų bazės lentelių. Sąryšinėje užklausoje nurodomos lentelės ir jų sąryšio sąlyga. Tokiai užklausai suformuoti… …
2Query language — Query languages are computer languages used to make queries into databases and information systems. Broadly, query languages can be classified according to whether they are database query languages or information retrieval query languages. The… …
3Query optimization — is a function of many relational database management systems in which multiple query plans for satisfying a query are examined and a good query plan is identified. This may or not be the absolute best strategy because there are many ways of doing …
4Query by Example — (QBE) is a database query language for relational databases. It was devised by Moshè M. Zloof at IBM Research during the mid 1970s, in parallel to the development of SQL. It is the first graphical query language, using visual tables where the… …
5Relational Model/Tasmania — (RM/T) was published by E.F. Codd in 1979 and is the name given to a number of extensions to his original relational model (RM) published in 1970. The overall goal of the RM/T was to define some fundamental semantic units, at atomic and molecular …
6Query by Example — (Suche anhand von Beispielen) bezeichnet eine relationale Datenbankabfragesprache, die von Moshé M. Zloof bei IBM parallel zu System R entwickelt wurde. Sie beruht im Wesentlichen auf dem Bereichskalkül. Dabei wird die Abfrage nicht wie in SQL… …
7Relational 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 …
8Relational 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 …
9Relational 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… …
10Query optimizer — The query optimizer is the component of a database management system that attempts to determine the most efficient way to execute a query. The optimizer considers the possible query plans for a given input query, and attempts to determine which… …
