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
, 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
, 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 (http://jcc.com/sql_stnd.html).
An SQL parser (ftp://ftp.ora.com/published/oreilly/nutshell/lexyacc/) is described in "Lex & Yacc", by Levine, Mason & Brown published by O'Reilly.
The 1995 SQL Reunion: People, Projects, and Politics (http://mcjones.org/System_R/SQL_Reunion_95/).
["A Guide to the SQL Standard", C.J. Date, A-W 1987].
["SQL for Dummies", Allen G. Taylor, IDG Books Worldwide].