From LQWiki

SQL is a standardized nonprocedural programming language that is used to manipulate data and database objects. Although it's standardized, some database vendors like Oracle and Microsoft use their own slightly modified versions of SQL.

Note: according to Chris Fehily, author of SQL Quick Start Guide, SQL is not an acronym and does not stand for structured query language. It isn't structured, it isn't limited to queries, and it isn't a complete language. He also says it is inaccurate to pronounce it "sequel", it's pronounced "Ess Queue Ell", or just enunciate the letters SQL.

See also

• databases
• database tools