Database Introduction: Database and Users of a Database

Database is a collection of interrelated information/data, so that it is available to many users for different purposes. The content of database is retrieved by combining data from all the different sources in an organization, so that data is available to all users and redundant data can be eliminated or minimized. A computer database gives us some electronic filling system which has a large number of ways of cross referencing g and this allows the user many different ways in which to reorganize and retrieve data. Databases play a critical role in almost all areas where computers are used, including business, law, engineering, medicines, education, library science, etc.

The management of data in database system is done by means of a general purpose software package called database management system. The database management system is the major software component of a database system. Some commercially available DBMS are INGRES, ORACLE, and Sybase.

DBMS works as an intermediary between the users and the database as salesperson in a consumer's distributor system. Consumer specifies the desired item by filling out an order form and submits it to a salesperson at the counter. The salesperson presents the items to the consumers after they have been retrieved. Similarly, the DBMS will take care of retrieving the data and data base user need to know what data he/she requires.

Components of Database

There are 4 major components of a database namely data, hardware, software and users. Let us discuss each of these briefly:

Data

The data stored in the system is partitioned into one or more database. A database is both integrated and shared. By Integrated, we mean that several different files are combined to eliminate the redundancy.

By shared we mean that several different users can share same piece of data or same user can access several different files..

Hardware

The hardware consists of secondary storage volumes - disks, drums, etc. on which the database resides, together with the associated devices, control unit, channels, and so forth.

Software

Between the hardware and the user there is a layer of software, usually called the database management system or DBMS. All requests from users to the database are handled by the DBMS.

Users

There are 3 classes of users:

i. Application Programmer

Application programmer is responsible for writing the application program (s) that uses the database in the languages like COBOL or PL/1 to meet the user requirement.

ii. End-Users

The second class of user is the end user who accesses the database from a terminal. They are further divided into 2 categories:

Casual Users

These users access the data from database using online query language by entering queries at terminal.

Naïve Users

Naïve users access data through application programs. They don't need to know any details of a structure or language of DBMS.

iii. DBA

DBA is a person or group of persons responsible for overall control of database. DBA decides the information content of database system , hardware device to be used, decides the users & the data to be used by users, deciding the backup and recovery method, validation check and monitoring the performance and responding to the changing requirements.