The Full form of SQL is Structured Query Language. SQL is generally pronounced as see-well. It is a widely-used programming language designed for working with Relational Database Management System. It was named as Structured English Query Language (SEQUEL) initially that is designed to add, update or remove data from within a database. Later, it changed its name to Structured Query Language (SQL).

SQL is originally based upon Tuple Relational Calculus and Relational Algebra. It was developed in the early 1970s at IBM by Donald D. Chamberlin and Raymond F. Boyce. SQL was first introduced in 1979 by Oracle Corporation as a commercial database system. Historically, SQL has been the favorite query language for database management systems running on mainframes and minicomputers.

Increasingly, however, SQL is being supported by PC database systems because it supports distributed databases (databases that are spread out over several computer systems). This enables several users on a (LAN) local-area network to access the same database simultaneously. In 1986, ANSI approved a rudimentary version of SQL as the official standard, but most versions of SQL since then have included many extensions to the ANSI standard. ANSI updated the standard in 1991. The new standard is known as SAG SQL.