SQL, Structured Query Language, is the standard language for defining and querying relational databases. It began at IBM Research in San Jose, California, where Donald D. Chamberlin and Raymond F. Boyce designed a language they called SEQUEL, short for Structured English Query Language. Their 1974 paper, “SEQUEL: A Structured English Query Language,” presented at the ACM SIGFIDET workshop, described a language built on Edgar Codd’s relational model.
The IBM paper explains that SEQUEL was meant to let people retrieve data from relational tables using a “consistent set of keyword English templates which reflect how people use tables to obtain information.” The abstract notes that the language has power equivalent to first-order predicate calculus while avoiding the bound variables and quantifiers that made earlier formal query languages hard for ordinary users. The name was later shortened to SQL.
SQL is declarative: the programmer describes what data is wanted rather than writing step-by-step instructions for how to fetch it, leaving the database system to choose an efficient execution plan. A single language covers defining tables, inserting and updating rows, and expressing queries that filter, join, group, and aggregate data.
SQL was standardized by ANSI and ISO in the 1980s. The U.S. federal FIPS PUB 127 standard of 1987 adopted the ANSI database language SQL by reference, one of several official endorsements that made SQL portable across many vendors’ systems. That standardization, combined with its origins in IBM’s relational research, helped SQL become and remain the dominant database language for decades.