Introduction
to Database
A database is a shared collection
of related data used to support the activities of a particular organization. A
database can be viewed as a repository of data that is defined once and then
accessed by various users.
A database has the following
properties:
• It is a representation of some
aspect of the real world or a collection of data elements (facts) representing
real-world information.
• A database is logical, coherent
and internally consistent.
• A database is designed, built and
populated with data for a specific purpose.
• Each data item is stored in a
field.
• A combination of fields makes up
a table. For example, each field in an employee table contains data about an
individual employee.
Database Management System
A database management system (DBMS)
is a collection of programs that enables users to create and maintain databases
and control all access to them. The primary goal of a DBMS is to provide an
environment that is both convenient and efficient for users to retrieve and
store information. A database-management system (DBMS) is a collection of
interrelated data and a set of programs to access those data. This is a
collection of related data with an implicit meaning and hence is a database.
The collection of data, usually referred to as the database, contains
information relevant to an enterprise. The primary goal of a DBMS is to provide
a way to store and retrieve database information that is both convenient and
efficient. By data, we mean known facts that can be recorded and that have
implicit meaning. For example, consider the names, telephone numbers, and
addresses of the people you know. You may have recorded this data in an indexed
address book, or you may have stored it on a diskette, using a personal
computer and software such as DBASE IV or V, Microsoft ACCESS, or EXCEL. A
datum – a unit of data – is a symbol or a set of symbols that are used to
represent something. This relationship between symbols and what they represent
is the essence of what we mean by information. Hence, information is
interpreted data – data supplied with semantics. Knowledge refers to the
practical use of information. While information can be transported, stored or
shared without many difficulties the same can not be said about knowledge.
Knowledge necessarily involves personal experience. Referring back to
the scientific experiment, a third person reading the results will have
information about it, while the person who conducted the experiment personally will
have knowledge about it.
Database systems are designed to
manage large bodies of information. Management of data involves both defining
structures for the storage of information and providing mechanisms for the
manipulation of information. In addition, the database system must ensure the
safety of the information stored, despite system crashes or attempts at
unauthorized access. If data are to be shared among several users, the system
must avoid possible anomalous results.
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