relational database management system
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{{worldwide}}{{Refimprove|date=March 2009}}{{Expand|date=March 2009}}A
relational database management system (RDBMS) is a
database management system (DBMS) that is based on the
relational model as introduced by
E. F. Codd. Most popular commercial and open source databases currently in use are based on the relational database model.A short definition of an RDBMS may be a DBMS in which data is stored in the form of tables and the relationship among the data is also stored in the form of tables.
Historical usage of the term
E. F. Codd introduced the term in his (wikt:seminal|seminal) paper
"A Relational Model of Data for Large Shared Data Banks", published in 1970. In this paper and later papers he defined what he meant by
relational. One well-known definition of what constitutes a relational database system is
Codd's 12 rules. However, many of the early implementations of the relational model did not conform to all of Codd's rules, so the term gradually came to describe a broader class of database systems. At a minimum, these systems:
- presented the data to the user as relations (a presentation in tabular form, i.e. as a collection of tables with each table consisting of a set of rows and columns, can satisfy this property)
- provided relational operators to manipulate the data in tabular form
The first systems that were relatively faithful implementations of the relational model were from the University of Michigan;
Micro DBMS (1969) and from IBM UK Scientific Centre at Peterlee;
IS1 (1970–72) and its followon
PRTV (1973–79). The first system sold as an RDBMS was
Multics Relational Data Store, first sold in 1978. Others have been
Berkeley Ingres QUEL and
IBM BS12.The most popular definition of an RDBMS is a product that presents a view of data as a collection of rows and columns, even if it is not based strictly upon
relational theory. By this definition, RDBMS products typically implement some but not all of Codd's 12 rules. A second, theory-based school of thought argues that if a database does not implement all of Codd's rules (or the current understanding on the relational model, as expressed by
Christopher J Date,
Hugh Darwen and others), it is not relational. This view, shared by many theorists and other strict adherents to Codd's principles, would disqualify most DBMSs as not relational. For clarification, they often refer to some RDBMSs as
Truly-Relational Database Management Systems (TRDBMS), naming others
Pseudo-Relational Database Management Systems (PRDBMS).As of 2009, most commercial relational DBMSes employ
SQL as their
query language. Alternative query languages have been proposed and implemented, notably the pre-1996 implementation of Berkeley Ingres QUEL. With standardization of the SQL, both commercial and open source DBMSes have adopted some degree of standards compliance.
Market structure
While relational database systems remain the dominant choice for both
transactional and analytical applications, newer structures are competing with RDBMSs in
data warehouse applications including
column-oriented and
correlation database systems.
See also
External links
{{Databases}}
RDBMSSistema administrador de bases de datos relacionalesRelational database management systemRelációs adatbázis-kezelő関係データベース管理システムRDBMSРеляционная СУБДСистем за управљање релационим базама податакаİlişkisel veri tabanı yönetim sistemiРеляційна СКБДHệ quản trị cơ sở dữ liệu quan hệ
- content above as imported from The Pseudopedia
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- time: 1:16pm EDT - Thu, Jul 29 2010
