Editing Relational database (section)

==History==
The concept of relational database was defined by [[Edgar F. Codd|E. F. Codd]] at [[IBM]] in 1970. Codd introduced the term ''relational'' in his research paper "A Relational Model of Data for Large Shared Data Banks".<ref name="codd" /> In this paper and later papers, he defined what he meant by ''relation''. One well-known definition of what constitutes a relational database system is composed of [[Codd's 12 rules]].

However, no commercial implementations of the relational model conform to all of Codd's rules,<ref>{{cite book |last=Date |first=Chris |title=Database in depth: relational theory for practitioners |date=5 May 2005 |publisher=O'Reilly |isbn=0-596-10012-4}}</ref> so the term has gradually come to describe a broader class of database systems, which at a minimum:

# Present the data to the user as [[relation (database)|relations]] (a presentation in tabular form, i.e. as a ''collection'' of [[table (database)|tables]] with each table consisting of a set of [[Row (database)|rows]] and [[Column (database)|columns]]);
# Provide [[relational operator]]s to manipulate the data in tabular form.

In 1974, IBM began developing [[IBM System R|System R]], a research project to develop a prototype RDBMS.<ref>
{{cite book
|date=8 Jan 1999
|title=Funding a Revolution: Government Support for Computing Research
|publisher=National Academies Press
|isbn=0309062780
|url={{google books |plainurl=y |id=wvCbAgAAQBAJ}}
}}</ref><ref>{{cite book
|last1=Sumathi |first1=S. |last2=Esakkirajan |first2=S.
|date=13 Feb 2008
|title=Fundamentals of Relational Database Management Systems
|publisher=Springer
|isbn=978-3540483977
|quote=The product was called SQL/DS (Structured Query Language/Data Store) and ran under the DOS/VSE operating system environment}}</ref>
The first system sold as an RDBMS was [[Multics Relational Data Store]] (June 1976).<ref>{{cite news |last1=Leavitt |first1=Don |title=MDBM' Backs Network, Relational Approaches |url=https://books.google.com/books?id=OohpOVF5L-IC&pg=PA11 |work=Computerworld |publisher=IDG Enterprise |date=6 September 1976 |language=en}}</ref><ref>{{cite book |last1=Schmidt |first1=Joachim W. |last2=Brodie |first2=Michael L. |title=Relational Database Systems: Analysis and Comparison |date=1982 |publisher=Springer Science & Business Media |isbn=978-3-642-68847-8 |pages=181–220 |url=https://books.google.com/books?id=E9upCAAAQBAJ&pg=PA185 |language=en}}</ref>{{citation needed|reason=Due to significance of nature of claim, specific unambiguous cite that it is indeed the first is required|date=January 2025}} [[Oracle Database|Oracle]] was released in 1979 by Relational Software, now [[Oracle Corporation]].<ref>{{cite journal |date=May 2007 |title=Oracle Timeline |journal=Profit Magazine |publisher=Oracle |volume=12 |issue=2 |page=26 |url=http://www.oracle.com/us/corporate/profit/p27anniv-timeline-151918.pdf |access-date=2013-05-16}}</ref> [[Ingres (database)|Ingres]] and [[IBM BS12]] followed. Other examples of an RDBMS include [[IBM Db2]], [[Adaptive Server Enterprise|SAP Sybase ASE]], and [[IBM Informix|Informix]]. In 1984, the first RDBMS for [[Macintosh 128K|Macintosh]] began being developed, code-named Silver Surfer, and was released in 1987 as [[4th Dimension (Software)|4th Dimension]] and known today as 4D.<ref>{{cite web |title=New Database Software Program Moves Macintosh Into The Big Leagues |website=tribunedigital-chicagotribune |date=28 June 1987 |url=https://www.chicagotribune.com/1987/06/28/new-database-software-program-moves-macintosh-into-the-big-leagues/ |access-date=2016-03-17}}</ref>

The first systems that were relatively faithful implementations of the relational model were from:

* University of Michigan – [[MICRO Relational Database Management System|Micro DBMS]] (1969)<ref name=ST_1>{{cite journal| title=A set theoretic data structure and retrieval language| author1=Hershey, W.R.|  author2=Easthope, C.H.| url=https://dl.acm.org/doi/10.1145/1095495.1095500| publisher=[[Association for Computing Machinery]]| journal=ACM SIGIR Forum| volume=7| issue=4| pages=45–55| date=1 December 1972| access-date=4 January 2024| doi=10.1145/1095495.1095500| url-access=subscription}}</ref>
* Massachusetts Institute of Technology (1971)<ref name=SIG_1>{{cite book| title=SIGFIDET '74: Proceedings of the 1974 ACM SIGFIDET (Now SIGMOD) Workshop on Data Description, Access and Control: Data Models: Data-Structure-Set versus Relational| url=https://dl.acm.org/doi/book/10.1145/800297| publisher=[[Association for Computing Machinery]]| date=1 January 1975| doi=10.1145/800297| access-date=4 January 2024| isbn=978-1-4503-7418-7}}</ref>
* IBM UK Scientific Centre at Peterlee – [[IBM IS1|IS1]] (1970–72),<ref name=PS_1>{{cite book| title=The Peterlee IS/1 System| author=Notley, M.G.| url=https://scholar.google.com/scholar?lookup=0&q=NOTLEY,+M.G.+The+Peterlee+IS/1+System,+I.B.M.+(U.K.)+Scientific+Centre+Report,+March+1972.+UKSC-0018.&hl=en&as_sdt=0,5| publisher=IBM United Kingdom Scientific Centre| date=1972| access-date=4 January 2024}}</ref> and its successor, [[PRTV]] (1973–79).<ref name="Todd 1976">{{cite journal|title=The Peterlee Relational Test Vehicle - A System Overview|journal=IBM Systems Journal|year=1976|first=Stephen|last=Todd|volume=15|issue=4|pages=285–308|doi=10.1147/sj.154.0285}}</ref>

The most common 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).{{citation needed| reason=no references|date=January 2024}} <!-- It can also be said as the raw database management system.-->

As of 2009, most commercial relational DBMSs employ [[SQL]] as their [[query language]].<ref>{{cite journal |last1=Ramakrishnan |first1=Raghu |last2=Donjerkovic |first2=Donko |last3=Ranganathan |first3=Arvind |last4=Beyer |first4=Kevin S. |last5=Krishnaprasad |first5=Muralidhar |year=1998 |title=SRQL: Sorted Relational Query Language |journal=E Proceedings of SSDBM |url=http://pages.cs.wisc.edu/~beyer/papers/srql_ssdbm98.pdf}}</ref>

Alternative query languages have been proposed and implemented, notably the pre-1996 implementation of [[QUEL query languages|Ingres QUEL]].