A complete database system in an organization contains four components.

a() Hardware: The hardware is a set of physical devices on which a database resides. It consists of one or additional computers, disk drives, CRT terminals, printers, tape drivers, connecting cables and so on.

The computers used for processing the data in database may be mainframe, mini computers and personal computers. Mainframe and mini computers have usually been used on a stand-alone basis to support multiple users accessing a ordinary database. Personal computers are regularly used with stand-alone databases controlled and accessed by single user.
Disk drivers are the key storage mechanism for databases. Desktop computers, CRT terminals and printers are used for entering and retrieving information from database.

The success of database system has been a lot dependent on advances in hardware technology. A very large quantity of main memory and disk storage is necessary to keep and control a huge quantity of data stored in database.

b() Software: A database system includes two kinds of software:

1()General Purpose database management software typically known as database management system (DBMS).

2()Application software that uses DBMS facilities to control the database to attain a specific business functions.

Application software is normally written by programmers to solve specific company problem. It may be written in languages like COBOL or C or it may be written in a language supplied by DBMS like SQL. Application software utilizes the facilities of DBMS to way in and manipulate data in the database providing reports or documents needed for the information and processing needs of the company.

The DBMS is system software alike to an operating system. It provides a lot of services to end users and programmers.

DBMS usually provides most of the following services.

a.1.) a central data definition and data control facility known as a data dictionary/directory or catalogue.
b.2.) Data security and integrity mechanisms.
c.3.) Concurrent data access for multiple users.
d.4.) User-oriented data query, manipulation and reporting capabilities.
e.5.) Programmer-oriented application system development capabilities.