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Relational database#RDBMS

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+#REDIRECT [[Relational database#RDBMS]]
-{{peacock|date=May 2013}}
+{{short description|DBMS that is based on the relational model}}
-le tshwerwe ke libono?????
-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|E. F. Codd]], of IBM's [[IBM Almaden Research Center|San Jose Research Laboratory]]. Many popular databases currently in use are based on the [[relational database]] model.
+{{Redirect category shell|1=
-RDBMSs have become  a predominant choice for the storage of information in new databases used for financial records, manufacturing and logistical information, personnel data, and much more since the 1980s. Relational databases have often replaced legacy [[hierarchical database]]s and [[network database]]s because they are easier to understand and use. However, relational databases have been challenged by [[object database]]s, which were introduced in an attempt to address the [[object-relational impedance mismatch]] in relational database, and [[XML database]]s.{{citation needed|date=March 2013}}
+{{R from merge}}
+{{R to section}}
-==Market share==     LE TSHWERWE KE LIBONO????
+{{R with history}}
-According to research company [[Gartner]], the five leading commercial relational database vendors by revenue in 2011 were [[Oracle Corporation|Oracle]] (48.8%), [[IBM]] (20.2%), [[Microsoft]] (17.0%), [[SAP AG|SAP]] including [[Sybase]] (4.6%), and [[Teradata]] (3.7%).<ref>{{cite web|url=http://itknowledgeexchange.techtarget.com/eye-on-oracle/oracle-the-clear-leader-in-24-billion-rdbms-market/|date=2012-04-12|accessdate=2013-03-01|title=Oracle the clear leader in $24 billion RDBMS market}}</ref>
+{{R printworthy}}
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-The three leading [[open source]] implementations are [[MySQL]], [[PostgreSQL]], and [[SQLite]].  [[MariaDB]] is a prominent fork of MySQL prompted by Oracle's acquisition of MySQL AB.
-According to Gartner, in 2008, the percentage of database sites using any given technology were (a given site may deploy multiple technologies):<ref>{{cite web|url=http://www.mysql.com/why-mysql/marketshare/|accessdate=2013-03-01|title=Market Share}}</ref>
-* [[Oracle Database]] - 70%
-* [[Microsoft SQL Server]] - 68%
-* [[MySQL]] (Oracle Corporation) - 50%
-* [[IBM DB2]] - 39%
-* [[IBM Informix]] - 18%
-* [[Adaptive Server Enterprise|SAP Sybase Adaptive Server Enterprise]] - 15%
-* [[Sybase IQ|SAP Sybase IQ]] - 14%
-* [[Teradata]] - 11%
-According to DB-Engines, the most popular systems are [[Oracle Corporation|Oracle]], [[MySQL]], [[Microsoft SQL Server]], [[PostgreSQL]] and [[IBM DB2]].<ref>{{cite web|url=http://db-engines.com/en/ranking/relational+dbms|accessdate=2013-05-06|title=DB-Engines Ranking of Relational DBMS}}</ref>
-==History==
-In 1974, IBM began developing [[IBM System R|System R]], a research project to develop a prototype RDBMS.<ref>
-{{cite book
-|title=Funding a Revolution: Government Support for Computing Research
-|publisher=National Academies Press
-|isbn=0309062780
-|date=8 Jan 1999
-|quote=System R did not convince IBM management to abandon its existing product}}</ref>  Its first commercial product was [[IBM SQL/DS|SQL/DS]], released in 1981.<ref>{{cite book
-|title=Fundamentals of Relational Database Management Systems
-|publisher=Springer
-|date=13 Feb 2008
-|isbn=3540483977
-|author=S. Sumathi, S. Esakkirajan
-|quote=The product was called SQL/DS (Structured Query Language/Data Store) and ran under the DOS/VSE operating system environment}}</ref> However, the first commercially available RDBMS was [[Oracle Database|Oracle]], released in 1979 by Relational Software, now [[Oracle Corporation]].<ref>{{cite journal |date=May 2007 |title=Oracle Timeline |magazine=Profit Magazine |volume=12 |issue=2 |page=26 |publisher=Oracle |format=PDF |accessdate=2013-05-16 |url=http://www.oracle.com/us/corporate/profit/p27anniv-timeline-151918.pdf}}</ref>
-Other examples of an RDBMS include [[IBM DB2|DB2]], [[Adaptive Server Enterprise|SAP Sybase ASE]], and [[IBM Informix|Informix]].
-==Historical usage of the term==
-The term "relational database" was invented by E. F. Codd at IBM in 1970, Codd introduced the term in his seminal paper "A Relational Model of Data for Large Shared Data Banks".<ref>[http://www.seas.upenn.edu/~zives/03f/cis550/codd.pdf "A Relational Model of Data for Large Shared Data Banks"]</ref> 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 composed of [[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, which at a minimum:
-* Present the data to the user as [[relation (database)|relation]]s (a presentation in tabular form, i.e. as a ''collection'' of [[table (database)|table]]s with each table consisting of a set of rows and columns);
-* Provide 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), the Massachusetts Institute of Technology;<ref>SIGFIDET '74 Proceedings of the 1974 ACM SIGFIDET (now SIGMOD) workshop on Data description, access and control</ref> (1971), and from IBM UK Scientific Centre at Peterlee; [[IBM IS1|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 model|relational theory]]. By this definition, RDBMS products typically implement some but not all of Codd's 12 rules.
-A second 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]].{{citation needed|date=February 2011}} Alternative query languages have been proposed and implemented, notably the pre-1996 implementation of Berkeley Ingres QUEL.
-==References==
-{{reflist}}
 {{DEFAULTSORT:Relational Database Management System}}
 [[Category:Relational model]]
-[[Category:Relational database management systems]]
+[[Category:Relational database management systems| ]]
-[[de:RDBMS]]
-[[hu:Relációs adatbázis-kezelő]]
-[[pl:RDBMS]]
-[[uk:Реляційна СКБД]]