< language , database , standard > /S Q L/ An industry-standard language for creating, updating and, querying relational database management systems .
SQL was developed by IBM in the 1970s for use in System R . It is the de facto standard as well as being an ISO and ANSI standard . It is often embedded in general purpose programming languages.
The first SQL standard, in 1986, provided basic language constructs for defining and manipulating tables of data; a revision in 1989 added language extensions for referential integrity and generalised integrity constraints . Another revision in 1992 provided facilities for schema manipulation and data administration , as well as substantial enhancements for data definition and data manipulation.
Development is currently underway to enhance SQL into a computationally complete language for the definition and management of persistent , complex objects. This includes: generalisation and specialisation hierarchies, multiple inheritance , user defined data types , triggers and assertions , support for knowledge based systems , recursive query expressions , and additional data administration tools. It also includes the specification of abstract data types (ADTs), object identifiers, methods , inheritance , polymorphism , encapsulation , and all of the other facilities normally associated with object data management.
The emerging SQL3 standard is expected to be complete in 1998.
According to Allen G. Taylor, SQL does _not_ stand for "Structured Query Language". That, like "SEQUEL" (and its pronunciation /see'kw*l/), was just another unofficial name for a precursor of SQL. However, the IBM SQL Reference manual for DB2 and Craig Mullins's "DB2 Developer's Guide" say SQL _does_ stand for "Structured Query Language".
SQL Standards .
An SQL parser is described in "Lex & Yacc", by Levine, Mason & Brown published by O'Reilly.
The 1995 SQL Reunion: People, Projects, and Politics .
["A Guide to the SQL Standard", C.J. Date, A-W 1987].
["SQL for Dummies", Allen G. Taylor, IDG Books Worldwide].
(2000-07-07)