SQL
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Ted 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 quasi-relational database management system, System R, which a group at IBM San Jose Research Laboratory had developed during the 1970s.
IBM Db2 Family
In 1974, the IBM San Jose Research center developed a relational DBMS, System R, to implement Codd's concepts. A key development of the System R project was SQL. To apply the relational model, Codd needed a relational-database language he named DSL/Alpha. At the time, IBM didn't believe in the potential of Codd's ideas, leaving the implementation to a group of programmers not under Codd's supervision, who violated several fundamentals of Codd's relational model; the result was Structured English QUEry Language or SEQUEL.