An influential paper, A Relational Model of Data for Large Shared Data Banks, by Dr. Edgar F. Codd, was published in June 1970 in the Association for Computing Machinery (ACM) journal, Communications of the ACM, although drafts of it were circulated internally within IBM in 1969. Codd's model became widely accepted as the definitive model for relational database management systems (RDBMS or RDMS).
During the 1970s, a group at IBM's San Jose research center developed a database system "System R" based upon Codd's model. Structured English Query Language ("SEQUEL") was designed to manipulate and retrieve data stored in System R. The acronym SEQUEL was later condensed to SQL because the word 'SEQUEL' was held as a trademark by the Hawker Siddeley aircraft company of the UK. Although SQL was influenced by Codd's work, Donald D. Chamberlin and Raymond F. Boyce at IBM were the authors of the SEQUEL language design. Their concepts were published to increase interest in SQL.
The first non-commercial, relational, non-SQL database, Ingres, was developed in 1974 at U.C. Berkeley.
In 1978, methodical testing commenced at customer test sites. Demonstrating both the usefulness and practicality of the system, this testing proved to be a success for IBM. As a result, IBM began to develop commercial products based on their System R prototype that implemented SQL, including the System/38 (announced in 1978 and commercially available in August 1979), SQL/DS (introduced in 1981), and DB2 (in 1983).
At the same time, Relational Software, Inc. (now Oracle Corporation) saw the potential of the concepts described by Chamberlin and Boyce and developed their own version of a RDBMS for the Navy, CIA and others. In the summer of 1979, Relational Software, Inc. introduced Oracle V2 (Version2) for VAX computers as the first commercially available implementation of SQL. Oracle V2 beat IBM's release of the System/38 to the market by a few weeks.
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