資料來源 : pyDict

結構式查詢語言

資料來源 : Free On-Line Dictionary of Computing

SQL
     
         /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 (http://www.jcc.com/sql_stnd.html)}.
     
        {An SQL parser
        (ftp://ftp.uu.net/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://www.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].
     
        (2000-07-07)