History of SQL

In June, 1970 Dr. Edgar F. Codd published a seminal paper, "A Relational Model of Data for Large Shared Data Banks". Codd's model became widely accepted as the definitive model for relational database management systems (RDBMS). After Codd published this paper, two projects were started to test its viability: Ingress at UC Berkeley in 1970, and later SystemR at IBM's San Jose research center in 1974-75. Ingress (INteractive Graphics REtrieval System) used QUEL (QUEry Language) as a query language and SystemR used SEQUEL.
The term SEQUEL was originally coined as a pun on QUEL (since it came after QUEL it was named sequel). In 1977, Revised SEQUEL/2 was defined. This was later renamed to SQL due to a trademark dispute (the word 'SEQUEL' was held as a trademark by the Hawker-Siddeley aircraft company of the UK). Although these query languages were greatly influenced by Codd's work, they were not designed by Codd himself; the QUEL language design was due to Michael Stonebraker at UC Berkeley, and the SEQUEL language design was due to Donald Chamberlin and Raymond Boyce at IBM. IBM published their concepts to increase interest in SEQUEL (later SQL).

Milestones in RDBMS development
1970 Dr. E. F. Codd publishes his first paper on the relational model
UC Berkeley INGRES prototype work begins
1974 IBM SEQUEL language and prototype developed
IBM System R Prototype work begins
1977 Relational Software Inc. (RSI) founded
Revised SEQUEL/2 (subsequently renamed SQL) defined
1979 Teradata Corporation formed
Britton-Lee, Inc. (later renamed ShareBase)formed
Oracle released by RSI (now Oracle Corporation)
1981 SQL/DS for VSE announced by IBM
INGRES for VAX/VMS announced by Oracle Corporation
1983 DB2 for MVS announced by IBM
1984 First DBC/1012 database machine shipped by Teradata
1985 Teradata acquired Britton-Lee
1986 First version of SQL standard released
Sybase Inc. formed
1987 NonStop SQL announced by Tandem
1988 Microsoft, Sybase and Ashton-Tate develop Sybase for OS/2
1992 AT&T purchases NCR and Teradata
1993 Microsoft and Sybase end partnership
Microsoft rebrands Sybase as SQL Server and releases Windows version
1995 Computer Associates acquires INGRES as a part of its Ask Group purchase
1997 NCR becomes independent company
1998 In-database OLAP and data mining appear in RDBMSs
2000 RDBMSs continue to add OO capabilities and support for complex data
2001 Native XML support is provided for the first time in an RDBMS
2003 W3C enhances XQuery, the XML query language
2004 SQL:2003 standard is published