sequel

SEQUEL, later known as SQL, refers to the original name and early design of the Structured Query Language used in relational database systems. It was developed in the 1970s by IBM researchers Donald D. Chamberlin and Raymond F. Boyce as part of the System R project, with the aim of providing a high-level, declarative language for querying and managing data in relational databases.

Origin and naming: The acronym SEQUEL stood for Structured English Query Language. In the late 1970s, due to trademark concerns, the name was shortened to SQL (Structured Query Language). The language then underwent standardization and broad adoption across database platforms.

Design and features: SQL is a declarative, non-procedural language that supports data definition, data manipulation, and data control, as well as transaction control. Core statements include those for querying data (SELECT), inserting, updating, and deleting records (INSERT, UPDATE, DELETE), and managing schemas (CREATE, ALTER, DROP). It also provides mechanisms for defining constraints, granting permissions, and controlling transactions (COMMIT, ROLLBACK, SAVEPOINT).

Standardization and influence: SQL has become the dominant standard for relational databases and is implemented by major systems such as Oracle, MySQL, PostgreSQL, Microsoft SQL Server, and IBM Db2. Over time, standards including SQL-92 and later revisions expanded features to cover triggers, stored procedures, and XML support, among others.

Legacy and usage: The term SEQUEL is largely historical, with modern references and usage centered on SQL. The distinction is primarily of historical interest, reflecting the language’s origins before the widespread adoption and standardization of SQL.