Editing Edgar F. Codd (section)

== Work ==
Codd received a PhD in 1965 from the University of Michigan, Ann Arbor, advised by [[John Henry Holland]].<ref name="mathgene"/><ref name="Independent">{{cite news|first=Martin|last= Campbell-Kelly |date=1 May 2003|title=Edgar Codd|newspaper=The Independent|url=https://www.independent.co.uk/news/obituaries/edgar-codd-730256.html|archive-url=https://web.archive.org/web/20101209234347/https://www.independent.co.uk/news/obituaries/edgar-codd-730256.html|url-status=live|access-date=24 October 2011|archive-date=9 December 2010}}</ref><ref name="coddphd">{{cite thesis |degree=PhD |first=Edgar|last=Codd |title=Propagation, Computation, and Construction in Two-dimensional cellular spaces |publisher=University of Michigan |date=1965 |author-link= Edgar F. Codd|id={{ProQuest|302172044}}}}</ref> His thesis was about [[self-replication]] in [[cellular automata]], extending on work of [[John von Neumann|von Neumann]] and showing that a set of eight states was sufficient for [[universal computation]] and [[Von Neumann universal constructor|construction]].<ref>{{cite book |last=Codd |first=Edgar Frank |title=Cellular Automata |publisher=Academic Pr |location=London |year=1968 |isbn=978-0-12-178850-6 }}</ref> [[Codd's cellular automaton|His design for a self-replicating computer]] was implemented only in 2010.

In the 1960s and 1970s, he worked out his theories of data arrangement, issuing his paper "A Relational Model of Data for Large Shared Data Banks"<ref name="relationalmodel">{{cite journal |last1= Codd |first1=Edgar Frank |date=June 1970 |title=A Relational Model of Data for Large Shared Data Banks |url=https://www.seas.upenn.edu/~zives/03f/cis550/codd.pdf |archive-url= https://web.archive.org/web/20040908011134/http://www.seas.upenn.edu/~zives/03f/cis550/codd.pdf |archive-date=2004-09-08 |url-status=live |journal=Communications of the ACM |volume=13 |issue= 6 |pages=377–87 |doi=10.1145/362384.362685 |s2cid=207549016 |access-date=2020-04-29}}</ref> in 1970, after an internal IBM paper one year earlier.<ref>Michael Owens. The Definitive Guide to SQLite, p. 47. New York: Apress (Springer-Verlag) 2006. {{ISBN|978-1-59059-673-9}}.</ref> To his disappointment, IBM proved slow to exploit his suggestions until commercial rivals started implementing them.<ref>{{cite news |title=Edgar F. Codd, 79, Dies; Key theorist of database |url=https://www.nytimes.com/2003/04/23/business/edgar-f-codd-79-dies-key-theorist-of-databases.html |access-date=7 September 2021 |work=The New York Times |date=23 April 2003}}</ref>

Initially, IBM refused to implement the relational model to preserve revenue from [[IMS/DB]], a [[Hierarchical database model|hierarchical database]] the company promoted in the 1970s.<ref>{{Cite book |last=O'Regan |first= Gerard |url=https://books.google.com/books?id=6u16DAAAQBAJ&pg=PA278 |title=Introduction to the History of Computing: A Computing History Primer |publisher=Springer |year=2016 |isbn=978-3-319-33138-6 |location=Dordrecht |page =278}}</ref>  Codd then showed IBM customers the potential of the implementation of its model, and they, in turn, pressured IBM. Then IBM included in its [[IBM Future Systems project|Future Systems]] project a [[IBM System R|System R]] subproject – but put in charge of it developers who were not thoroughly familiar with Codd's ideas, and isolated the team from Codd.<ref name="Chamberlin 2011 oral history">{{cite web | last=Chamberlin | first=D. D. (Donald Dean) | title=Oral history interview with Donald D. Chamberlin | publisher=Charles Babbage Institute | date=2011-06-08 | hdl=11299/107215 | url=https://conservancy.umn.edu/handle/11299/107215 | access-date=2024-02-14}}</ref><ref name="IBM Edgar F. Codd">{{cite web | title=Edgar F. Codd | website=IBM | url=https://www.ibm.com/history/edgar-codd | access-date=2024-02-14}}</ref> As a result, they did not use Codd's own [[Alpha (programming language)|Alpha]] language but created a non-relational one, SEQUEL. Even so, SEQUEL was so superior to pre-relational systems that in 1979 it was copied by [[Larry Ellison]], based on pre-launch papers presented at conferences of Relational Software Inc, in his [[Oracle Database]], which actually reached the market before [[IBM SQL/DS|SQL/DS]] – because of the then-already proprietary status of the original name, SEQUEL had to be renamed to [[SQL]].

Codd continued to develop and extend his relational model, sometimes in collaboration with [[Christopher J. Date]].<ref>{{Cite book |last=Celko |first=Joe |title=Joe Celko's Data and Databases: Concepts in Practice |publisher=Morgan Kaufmann Publishers |year=1999 |isbn=1-55860-432-4 |location=San Francisco, CA |page =124}}</ref> One of the [[Database normalization|normalised forms]], the [[Boyce–Codd normal form]], is named after him.<ref name="Codd">Codd, E. F. 1974 "Recent Investigations into Relational Data Base" in ''Proc. 1974 Congress''. Stockholm, Sweden; New York, NY: North-Holland.</ref>

[[Codd's theorem]], a result proven in his seminal work on the relational model, equates the expressive power of [[relational algebra]] and [[relational calculus]].<ref name="relationalmodel"/>

As the relational model became fashionable in the early 1980s, Codd fought a sometimes bitter campaign to prevent the term from being misused by database vendors who had merely added a relational veneer to older technology. As part of this campaign, he published his [[Codd's 12 rules|12 rules]] to define what constituted a relational database. This made his position at IBM increasingly difficult, so he left to form a consulting company with Chris Date and others.

Codd coined the term ''[[Online analytical processing|Online analytical processing (OLAP)]]'' and wrote the "twelve laws of online analytical processing".<ref>Providing OLAP to User-Analysts: An IT Mandate by E F Codd, S B Codd and C T Salley, ComputerWorld, 26 July 1993.</ref> Controversy erupted, however, after it was discovered that this paper had been sponsored by [[Oracle Hyperion|Arbor Software]] (subsequently Hyperion, now acquired by Oracle), a conflict of interest that had not been disclosed, and ''[[Computerworld]]'' withdrew the paper.<ref name= "The Register 2007-01-26">{{cite web|url=https://www.theregister.co.uk/2007/01/26/olap_speed/|title=OLAP and the need for Speed |last=Whitehorn|first=Mark|date=26 January 2007 |website= [[The Register]]|access-date=30 December 2014}}</ref>

In 2004, [[SIGMOD]] renamed its highest prize to the [[SIGMOD Edgar F. Codd Innovations Award]], in his honour.