<database> (DBMS) A suite of programs which typically manage
	large structured sets of persistent data, offering ad hoc
	query facilities to many users.  They are widely used in
	business applications.

	A database management system (DBMS) can be an extremely
	complex set of software programs that controls the
	organisation, storage and retrieval of data (fields, records
	and files) in a database.  It also controls the security and
	integrity of the database.  The DBMS accepts requests for data
	from the application program and instructs the operating
	system to transfer the appropriate data.

	When a DBMS is used, information systems can be changed much
	more easily as the organisation's information requirements
	change.  New categories of data can be added to the database
	without disruption to the existing system.

	Data security prevents unauthorised users from viewing or
	updating the database.  Using passwords, users are allowed
	access to the entire database or subsets of the database,
	called subschemas (pronounced "sub-skeema").  For example, an
	employee database can contain all the data about an individual
	employee, but one group of users may be authorised to view
	only payroll data, while others are allowed access to only
	work history and medical data.

	The DBMS can maintain the integrity of the database by not
	allowing more than one user to update the same record at the
	same time.  The DBMS can keep duplicate records out of the
	database; for example, no two customers with the same customer
	numbers (key fields) can be entered into the database.

	{Query languages} and {report writers} allow users to
	interactively interrogate the database and analyse its data.

	If the DBMS provides a way to interactively enter and update
	the database, as well as interrogate it, this capability
	allows for managing personal databases.  However, it may not
	leave an audit trail of actions or provide the kinds of
	controls necessary in a multi-user organisation.  These
	controls are only available when a set of application programs
	are customised for each data entry and updating function.

	A business information system is made up of subjects
	(customers, employees, vendors, etc.) and activities (orders,
	payments, purchases, etc.).  Database design is the process of
	deciding how to organize this data into record types and how
	the record types will relate to each other.  The DBMS should
	mirror the organisation's data structure and process
	transactions efficiently.

	Organisations may use one kind of DBMS for daily transaction
	processing and then move the detail onto another computer that
	uses another DBMS better suited for random inquiries and
	analysis.  Overall systems design decisions are performed by
	data administrators and systems analysts.  Detailed database
	design is performed by database administrators.

	The three most common organisations are the {hierarchical
	database}, {network database} and {relational database}.  A
	database management system may provide one, two or all three
	methods.  Inverted lists and other methods are also used.  The
	most suitable structure depends on the application and on the
	transaction rate and the number of inquiries that will be
	made.

	Database machines are specially designed computers that hold
	the actual databases and run only the DBMS and related
	software.  Connected to one or more mainframes via a
	high-speed channel, database machines are used in large volume
	transaction processing environments.  Database machines have a
	large number of DBMS functions built into the hardware and
	also provide special techniques for accessing the disks
	containing the databases, such as using multiple processors
	concurrently for high-speed searches.

	The world of information is made up of data, text, pictures
	and voice.  Many DBMSs manage text as well as data, but very
	few manage both with equal proficiency.  Throughout the 1990s,
	as storage capacities continue to increase, DBMSs will begin
	to integrate all forms of information.  Eventually, it will be
	common for a database to handle data, text, graphics, voice
	and video with the same ease as today's systems handle data.

	See also: {intelligent database}.

	(1998-10-07)

<database, programming> (JDBC) Part of the {Java Development
	Kit} which defines an {application programming interface} for
	{Java} for standard {SQL} access to {databases} from Java
	{programs}.

	{Home
	(http://java.sun.com/products/jdk/1.1/docs/guide/jdbc/index.html)}.

	{FAQ (http://www.yoyoweb.com/Javanese/JDBC/FAQ.html)}.

	See also {Open Database Connectivity}.

	(1997-09-04)

<programming> Waffle for "{features}" or "function".  The
	capabilities or behaviours of a program, part of a program, or
	system, seen as the sum of its {features}.  Roughly, "the
	things it can do".  Generally used in a comparative sense,
	e.g. "The latest update adds some useful functionality".

	(1997-07-14)

<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 (http://www.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://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].

	(2005-11-17)

<software> Instructions for a computer in some programming
	language, often {machine language}.  The word "code" is often
	used to distinguish instructions from {data} (e.g. "The code
	is marked 'read-only'") whereas "{software}" is used in
	contrast with "{hardware}" and may consist of more than just
	code.

	(2000-04-08)

{system administration}

What many users feel for computers.

	"I don't really love computers, I just say that to get them
	into bed with me". (Terry Pratchet)

	[What did you expect in a computing dictionary?]

	(1995-05-10)

1. <database, information science> A user's (or {agent}'s)
	request for information, generally as a formal request to a
	{database} or {search engine}.

	{SQL} is the most common {database query language}.

	2. <character> {question mark}.

	(1997-04-09)

1. <programming> A collection of identically typed data items
	distinguished by their indices (or "subscripts").  The number
	of dimensions an array can have depends on the language but is
	usually unlimited.

	An array is a kind of {aggregate} data type.  A single
	ordinary variable (a "{scalar}") could be considered as a
	zero-dimensional array.  A one-dimensional array is also known
	as a "{vector}".

	A reference to an array element is written something like
	A[i,j,k] where A is the array name and i, j and k are the
	indices.  The {C} language is peculiar in that each index is
	written in separate brackets, e.g. A[i][j][k].  This expresses
	the fact that, in C, an N-dimensional array is actually a
	vector, each of whose elements is an N-1 dimensional array.

	Elements of an array are usually stored contiguously.
	Languages differ as to whether the leftmost or rightmost index
	varies most rapidly, i.e. whether each row is stored
	contiguously or each column (for a 2D array).

	Arrays are appropriate for storing data which must be accessed
	in an unpredictable order, in contrast to {lists} which are
	best when accessed sequentially.

	See also {associative array}.

	2. <architecture> A {processor array}, not to be confused with
	an {array processor}.

	(1995-01-25)

<object-oriented> In {object-oriented programming}, an
	instance of the data structure and behaviour defined by the
	object's {class}.  Each object has its own values for the
	{instance variables} of its class and can respond to the
	{methods} defined by its class.

	For example, an object of the "Point" class might have
	instance variables "x" and "y" and might respond to the "plot"
	method by drawing a dot on the screen at those coordinates.

	(2004-01-26)

1. <hardware> {monitor}.

	2. <language> A vector of pointers to {activation records}.
	The Nth element points to the activation record containing
	variables declared at {lexical depth} N.  This allows faster
	access to variables from outer {scopes} than the alternative
	of linked activation records (but most variable accesses are
	either local or global or occasionally to the immediately
	enclosing scope).  Displays were used in some {ALGOL}
	implementations.

	(1996-02-22)

<programming, World-Wide Web> (JSP) A freely available
	specification for extending the {Java Servlet} {API} to
	generate dynamic {web pages} on a {web server}.  The JSP
	specification was written by industry leaders as part of the
	Java development program.

	JSP assists developers in creating {HTML} or {XML} pages that
	combine static (fixed) page templates with dynamic content.
	Separating the {user interface} from content generation allows
	page designers to change the page layout without having to
	rewrite program code.  JSP was designed to be simpler than
	pure servlets or {CGI} {scripting}.

	JSP uses XML-like tags and scripts written in Java to generate
	the page content.  HTML or XML formatting {tags} are passed
	back to the client.  Application logic can live on the server,
	e.g. in {JavaBeans}.

	JSP is a {cross-platform} alternative to {Microsoft's} {Active
	Server Pages}, which only runs in {IIS} on {Windows NT}.

	Applications written to the JSP specification can be run on
	compliant web servers, and web servers such as {Apache},
	{Netscape Enterprise Server}, and Microsoft {IIS} that have
	had Java support added.  JSP should soon be available on
	{Unix}, {AS/400}, and {mainframe} platforms.

	{JavaServer Pages (http://java.sun.com/products/jsp/)}.

	{Infoworld Article
	(http://www.infoworld.com/cgi-bin/displayStory.pl?99063.ecjsp.htm)}.

	(1999-11-28)

In {object-oriented programming} sending a message to an
	{object} (to invoke a {method}) is equivalent to calling a
	{procedure} in traditional programming languages, except that
	the actual code executed may only be selected at run time
	depending on the {class} of the object.  Thus, in response to
	the message "drawSelf", the method code invoked would be
	different if the target object were a circle or a square.

	(1995-02-16)