SQL
Structured Query Language
/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].
(2005-11-17)
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