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DATABASE
The earliest known use of the term 'data base' was in June 1963, when the
System Development Corporation sponsored a symposium under the title
Development and Management of a Computer-centered Data Base. Database as a
single word became common in Europe in the early 1970s and by the end of the
decade it was being used in major American newspapers. (Databank, a comparable
term, had been used in the Washington Post newspaper as early as 1966.)
The term database originated within the computer industry. A database is a
collection of records stored in a computer in a systematic way, so that a computer
program can consult it to answer questions. The items retrieved in answer to queries
become information that can be used to make decisions. The computer program used
to manage and query a database is known as a database management system
(DBMS). The properties and design of database systems are included in the study of
information science.
The central concept of a database is that of a collection of records or pieces of
knowledge. Typically, for a given database, there is a structural description of the
type of facts held in that database: this description is known as a schema. The schema
describes the objects that are represented in the database, and the relationships among
them. There are a number of different ways of organizing a schema, that is, of
modeling the database structure: these are known as database models (or data
models). The model in most common use today is the relational model, which in
layman's terms represents all information in the form of multiple related tables, each
consisting of rows and columns (the true definition uses mathematical terminology).
This model represents relationships by the use of values common to more than one
table. Other models such as the hierarchical model and the network model use a more
explicit representation of relationships.
Strictly speaking, the term database refers to the collection of related records,
and the software should be referred to as the database management system or DBMS.
When the context is unambiguous, however, many “database” administrators and
programmers use the term database to cover both meanings.
Many professionals would consider a collection of data to constitute a database
only if it has certain properties: for example, if the data is managed to ensure its
integrity and quality, if it allows shared access by a community of users, if it has a
schema, or if it supports a query language. However, there is no agreed definition of
these properties.
Database management systems are usually categorized according to the data
model that they support: relational, object-relational, network, and so on. The data
model will tend to determine the query languages that are available to access the
database. A great deal of the internal engineering of a DBMS, however, is
independent of the data model, and is concerned with managing factors such as
performance, concurrency, integrity, and recovery from hardware failures. In these
areas there are large differences between products.
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