relational database

n. A database system in which any field can be a component of more than one of the database's tables.

rela′tional da′tabase

n. an electronic database comprising multiple files of related information, usu. stored in tables of rows (records) and columns (fields), and allowing a link to be established between separate files that have a matching field, as a column of invoice numbers, so that the two files can be queried simultaneously by the user.

Thesaurus

Noun

relational database - a database in which relations between information items are explicitly specified as accessible attributes; "in a relational database the data are organized as a number of differently sized tables"computer database, electronic database, electronic information service, on-line database - (computer science) a database that can be accessed by computers

Translations

relational database

[ri′lā·shən·əl ′dad·ə‚bās] (computer science) relational system

relational database

(database)(RDBMS - relational database management system) Adatabase based on the relational model developed byE.F. Codd. A relational database allows the definition ofdata structures, storage and retrieval operations andintegrity constraints. In such a database the data andrelations between them are organised in tables. A table isa collection of rows or records and each row in a tablecontains the same fields. Certain fields may be designatedas keys, which means that searches for specific values ofthat field will use indexing to speed them up.

Where fields in two different tables take values from the sameset, a join operation can be performed to select relatedrecords in the two tables by matching values in those fields.Often, but not always, the fields will have the same name inboth tables. For example, an "orders" table might contain(customer_id, product_code) pairs and a "products" table mightcontain (product_code, price) pairs so to calculate a givencustomer's bill you would sum the prices of all productsordered by that customer by joining on the product-code fieldsof the two tables. This can be extended to joining multipletables on multiple fields. Because these relationships areonly specified at retreival time, relational databases areclassed as dynamic database management system.

The first commercial RDBMS was the Multics Relational Data Store, first sold in 1978.

INGRES, Oracle, Sybase, Inc., Microsoft Access, andMicrosoft SQL Server are well-known database products andcompanies. Others include PostgreSQL, SQL/DS, and RDB.

["Managing Data Bases, Four Critical Factors" MichaelM. Gorman, QED Information Sciences, Inc.].

["An Introduction To Database Systems" (6th ed) C. J. Date,Addison Wesley (an excellent source of detailed info)].

["An End-User's Guide to Data Base" James Martin, PrenticeHall (excellent place to begin learning about DBMS)].

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

relational database

relational database

rela′tional da′tabase

relational database

relational database

relational database

relational database

relational database

Words related to relational database

noun a database in which relations between information items are explicitly specified as accessible attributes

Related Words