A relational database is a database based on the relational model. Strictly speaking the term refers to a specific collection of data but it is often used synonymously with the software that is used to manage that collection of data. That software is more correctly called a relational database management system, or RDBMS. A database is an organized collection of data. ... The relational model for management of a database is a data model based on predicate logic and set theory. ... Data is the plural of datum. ... A relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model as introduced by Edgar F. Codd. ...
All data stored in and retrieved from a relational database is cast in the form of relations. A relation is a set of n-tuples that represents the extension of an n-adic predicate. However, these n-tuples are not the ordered tuples of mathematics; instead, their components, called attribute values, are identified and referenced by names. Queries and integrity constraints are expressed declaratively, without the use of iterative loops or pointers, using operators based on the relational algebra and relation comparisons. The relational algebra is complete with respect to first-order predicate calculus except that certain restrictions are imposed on the use of negation and disjunction to address problems of computability. In mathematics, a relation is a generalization of arithmetic relations, such as = and <, which occur in statements, such as 5 < 6 or 2 + 2 = 4. See relation (mathematics), binary relation and relational algebra. ... In mathematics, a tuple is a finite sequence of objects, that is, a list of a limited number of objects (an infinite sequence is a family). ... In mathematics, a predicate is a relation. ... The relational algebra is a set of operations that manipulate relations as they are defined in the relational model and as such describes part of the data manipulation aspect of this data model. ...
A dimensional database is one which, rather than storing data in multiple two dimensional tables (as a relational databases does), represents key data entities as different dimensions. ...
External links
A Relational Model of Data for Large Shared Data Banks: By Edgar F. Codd
Relational Database Principles by Colin Ritche. ISBN 0826457134 This is Very Helpful for courses where databases are a course module.
Database in Depth by Chris Date. ISBN 0596100124. A new book (2005) by perhaps the best-known author in this field.
This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.
A relationaldatabase is a database structured in accordance with the relational model.
The relational algebra is complete with respect to first-order predicate calculus except that restrictions are imposed on the use of the logical operations of negation and disjunction in order to guarantee that database computations will be feasible in practice.
The relational algebra is a set of operations that manipulate relations as they are defined in the relational model and as such describes part of the data manipulation aspect of this data model.
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