SQL began at IBM as the SEQUEL language described in Chamberlin and Boyce’s 1974 paper, but in its first decade each database vendor implemented its own dialect. The turning point came in 1986, when the American National Standards Institute, ANSI, adopted SQL as a national standard, designated X3.135-1986. The International Organization for Standardization, ISO, published a technically equivalent standard in 1987.
A standardized SQL mattered because it made the language portable. Before the standard, queries written for one vendor’s database often had to be rewritten to run on another’s. An agreed common core meant that programmers could learn one language and carry their skills and much of their code between systems from different vendors.
The U.S. federal government endorsed the new standard directly. FIPS PUB 127, “Database Language SQL,” issued in 1987, adopted the ANSI database language SQL by reference as a Federal Information Processing Standard, requiring conforming SQL in database systems bought by federal agencies. This kind of official adoption gave vendors a strong reason to converge on the standard.
The 1986 standard was only the beginning of a long line of revisions that added features over the following decades, but it established the principle that mattered most: SQL would be a shared, vendor-neutral language. That portability, layered on top of the relational model and proven implementations, is a central reason SQL became and remained the dominant database language.