<database> A collection of {records} in a {relational database}.

	(1997-06-04)

<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> A constant made available to a process, by
	inclusion in the executable text.  Most modern systems do not
	allow texts to modify themselves during execution, so literals
	are indeed constant; their value is written at compile-time
	and is read-only at run time.

	In contrast, values placed in variables or files and accessed
	by the process via a symbolic name, can be changed during
	execution.  This may be an asset.  For example, messages can
	be given in a choice of languages by placing the translation
	in a file.

	Literals are used when such modification is not desired.  The
	name of the file mentioned above (not its content), or a
	physical constant such as 3.14159, might be coded as a
	literal.  Literals can be accessed quickly, a potential
	advantage of their use.

	(1996-01-23)

A language proposed by Cii {Honeywell-Bull} to meet the DoD
	{Ironman} requirements which led to {Ada}.  This language won
	in 1979.

	["On the GREEN Language Submitted to the DoD", E.W. Dijkstra,
	SIGPLAN Notices 13(10):16-21 (Oct 1978)].

	(1994-12-02)

<operating system, security> An {operating system} security or
	access control model where specific types of access to a
	specific object are granted by giving a process this data
	structure or {token}.

	The token may be unforgeable (typically by using {encryption}
	or hardware "tagged" memory).  Capabilities are used in OSes
	such as {Hydra}, {KeyKOS}, {EROS}, {Chorus}/{Mix}, and the
	{Stanford V system}.  Similar to {Kerberos}, but in an OS
	context.

	Compare {access control list}.

	(1998-03-08)

<theory, programming> (Or "data type") A set of values from
	which a {variable}, {constant}, {function}, or other
	{expression} may take its value.  A type is a classification
	of data that tells the {compiler} or {interpreter} how the
	programmer intends to use it.  For example, the process and
	result of adding two variables differs greatly according to
	whether they are integers, floating point numbers, or strings.

	Types supported by most programming languages include
	{integers} (usually limited to some range so they will fit in
	one {word} of storage), {Booleans}, {floating point numbers},
	and characters.  {Strings} are also common, and are
	represented as {lists} of characters in some languages.

	If s and t are types, then so is s -> t, the type of
	{functions} from s to t; that is, give them a term of type s,
	functions of type s -> t will return a term of type t.

	Some types are {primitive} - built-in to the language, with no
	visible internal structure - e.g. Boolean; others are
	composite - constructed from one or more other types (of
	either kind) - e.g. {lists}, {arrays}, {structures}, {unions}.
	{Object-oriented programming} extends this with {classes}
	which encapsulate both the structure of a type and the
	operations that can be performed on it.

	Some languages provide {strong typing}, others allow {implicit
	type conversion} and/or {explicit type conversion}.

	(2003-12-22)

1. <programming> A common name for the {integer} data type.
	In {C} for example, it means a (signed) integer of the
	computer's native {word length}.

	2. <networking> The {top-level domain} for international
	organisations.

	(1999-01-26)

1. <application> Any specific type of {file} produced or
	edited by a specific {application}; usually capable of being
	printed.  E.g. "Word document", "Photoshop document", etc.

	2. <hypertext> A term used on some systems (e.g. {Intermedia})
	for a {hypertext} {node}.  It is sometimes used for a
	collection of nodes on related topics, possibly stored or
	distributed as one.

	3. <programming> To write {documentation} on a certain piece
	of code.

	(2003-10-25)

<networking> (Note: not capitalised) Any set of networks
	interconnected with {routers}.  The {Internet} is the biggest
	example of an internet.

	(1996-09-17)

<file format> (PDF) The native file format for {Adobe
	Systems}' {Acrobat}.  PDF is the file format for representing
	documents in a manner that is independent of the original
	application software, hardware, and operating system used to
	create those documents.  A PDF file can describe documents
	containing any combination of text, graphics, and images in a
	device-independent and {resolution} independent format.  These
	documents can be one page or thousands of pages, very simple
	or extremely complex with a rich use of {fonts}, graphics,
	colour, and {images}.

	{Home (http://www.adobe.com/products/acrobat/adobepdf.html)}.

	["The Portable Document Format Reference Manual", Adobe
	systems, Inc. Addison-Wesley Publ.  Co., ISBN: 0-201-62628-4].

	(2000-09-08)

<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)

<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)

<programming> (Or "arg") A value or reference passed to a
	{function}, {procedure}, {subroutine}, command or program, by
	the caller.  For example, in the function definition

		square(x) = x * x

	x is the {formal argument} or "parameter", and in the call

		y = square(3+4)

	3+4 is the {actual argument}.  This will execute the function
	square with x having the value 7 and return the result 49.

	There are many different conventions for passing arguments to
	functions and procedures including {call-by-value},
	{call-by-name}, {call-by-reference}, {call-by-need}.  These
	affect whether the value of the argument is computed by the
	caller or the callee (the function) and whether the callee can
	modify the value of the argument as seen by the caller (if it
	is a variable).

	Arguments to functions are usually, following mathematical
	notation, written in parentheses after the function name,
	separated by commas (but see {curried function}).  Arguments
	to a program are usually given after the command name,
	separated by spaces, e.g.:

		cat myfile yourfile hisfile

	Here "cat" is the command and "myfile", "yourfile", and
	"hisfile" are the arguments.

	(2006-05-27)

1. String processing language, combined the pattern matching
	and transformation operations of COMIT with the recursive data
	structures of Lisp.  "Convert", A. Guzman et al, CACM
	9(8):604-615 (Aug 1966).

	2. Early language to convert programs and data from one
	language to another.  "CONVERT Manual", OLI Systems Inc (Oct
	1976).