relational model


Also found in: Dictionary, Thesaurus, Acronyms, Wikipedia.
Related to relational model: Relational algebra

relational model

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

relational database

A database that maintains a set of separate, related files (tables), but combines data elements from the files for queries and reports when required. The concept was developed in 1970 by Edgar Codd, whose objective was to accommodate a user's ad hoc request for selected data. Most every business database management system (DBMS), including Oracle, DB2, SQL Server, MySQL, etc., is a relational DBMS (RDBMS) (see DBMS).

Hierarchical, Network and Object Databases
In non-relational "hierarchical" and "network" databases, records in one file contain embedded pointers to the locations of records in another, such as customers to orders and vendors to purchases. These are fixed links set up ahead of time to speed up daily processing. Another type of non-relational database is the "object database," which stores data consistent with their object model (see object database).

Comparing and Joining
Routine queries to a relational database often require data from more than one file. For example, to obtain the names of customers who purchased a particular product, data must be extracted from both the customer and order files. A relational DBMS has the flexibility to "join" two or more files by comparing key fields such as account number and name and generating a new file from the records that meet the matching criteria (see join).

Indexes Are Used
In practice, a pure relational query can be very slow. In order to speed up the process, indexes are built and maintained on the key fields used for matching. Sometimes, indexes are created "on the fly" when the data are requested.

Relational Terms       Common Term

  Table or Relation      File

  Row or Tuple           Record

  Column or Attribute    Field



Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
The change brought database structure, performance and data-availability problems which haven't been addressed by the previous relational model. With these weak spots and the need to manage huge chunks of data more efficiently, the NoSQL term appeared.
When you recognize that members of a community or group are using a different relational model to guide interactions, then you can more readily adjust your own thinking to match theirs, making more accurate situational assessments and forecasts about future actions.
Liu, "The parallel and uniform properties of several relational models," Systems Engineering, vol.
Therefore, we can use the relational model to define a database schema at L1, or we can use it to define itself at L2.
These present findings are consistent with the relational model of spirituality developed by Shults and Sandage (2006) suggesting that forms of spiritual dwelling would be consistent with the virtues of forgiveness and gratitude, while spiritual seeking and questing would often be related to spiritual disappointment and a less conciliatory approach to relationships.
Emphasis is given to those research works focusing on relational model. Section 4 presents our proposed approach while the achievement of the proposed approach is discussed in Section 5.
The output from a fuzzy relational model is given by
From the perspective of the Relational Model, women's relationships can promote healthy choices when those relationships are supportive and positive (Covington & Surrey 1997; Finkelstein 1996; Finkelstein & Piedade 1993).
The authors have used their experience as practitioners to illustrate their relational model and the book is peppered with clinical vignettes from their client population in an attempt to bridge theory with practice.
The most significant feature of the relational model is that all the facts are stored in tables, which are treated as mathematical relations.
We suggest that a theory-based relational model could offer a road map in assisting recovering men to discover a fuller experience of themselves and to transform their experience of recovery.

Full browser ?