SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the
relational model from Edgar F. Codd in the early 1970s.This version, initially called SEQUEL
(Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original
quasirelational database management system, System R, which a group at IBM San Jose Research Laboratory had
developed during the 1970s.
Chamberlin and Boyce's first attempt at a relational database language was SQUARE (Specifying Queries in A
Relational Environment), but it was difficult to use due to subscript/superscript notation. After moving to the
San Jose Research Laboratory in 1973, they began work on a sequel to SQUARE. The original name SEQUEL, which
is widely regarded as a pun on QUEL, the query language of Ingres, was later changed to SQL (dropping the
vowels) because "SEQUEL" was a trademark of the UK-based Hawker Siddeley Dynamics Engineering Limited
company. The label SQL later became the acronym for Structured Query Language.
After testing SQL at customer test sites to determine the usefulness and practicality of the system, IBM began
developing commercial products based on their System R prototype, including System/38, SQL/DS, and IBM Db2,
which were commercially available in 1979, 1981, and 1983, respectively.IBM's endorsement caused the
industry to move to SQL from alternatives like QUEL.