Introduction to Database System Definition Contents Components Advantages

Introduction to Database System

Definition Contents Components Advantages Limitations Definition Components Advantages Limitations Objectives Contents

Definition It is a computer based record keeping system whose overall purpose is to record & maintain the information. In other word, database system is a pool (reservoir) of data. It is composed of collection of files that are linked in such a way that information from one of the files may be combined with information from other files so that a user may receive the exact required information.

Definition Contd. . It is well organized collection of data that are related in a meaningful way which can be accessed in different logical orders that re stored only once. Database Users DBMS Users

Components of Database Data Hardware Software Users Data Hardware Software Users

Data It refers to values physically recorded in the database. Data stored in the system is partitioned into two or more files. But in general, data is integrated & shared. Integrated means that database may be thought of unification of several distinct files without any duplicacy.

Data Contd… Shared means individual piece of data may be shared between different users in the sense that each user may access the data. Concurrent sharing is also possible i. e. several users can access same data simultaneously at same time in different ways.

Hardware It consists of secondary storage devices like tape, disk etc. in which data is actually stored. It also consists of control unit and Input / output devices.

Software Between the physical database itself and users of the system there is a layer of software called DBMS. All requests from the users are handled by DBMS. In other word, DBMS protects the user from hardware level details.

Users Application Programmers End Users DBA (Database Administrator)

Users Contd. . Application Programmer : It writes the programs in some programming language to use the database. These programs operate the data in all the ways i. e. creating new information, deleting or changing existing information, retrieving information.

Users Contd. . End Users : The users who uses the programs written by programmer to work with database system. A end user may use query language or written program to issue a request.

Users Contd. . DBA : A DBA is a person or group of persons responsible for overall control of database system. A DBA may perform functions like deciding information contents, deciding storage structure & access strategies, defining strategies of backup & recovery etc.

Advantages of Database System Redundancy can be removed Inconsistency can be avoided Data can be shared Standards can be easily enforced Integrity can be maintained Conflicting requirements can be balanced Data Independence is there

Limitations of Database System Security Problem Privacy Problem Sophisticated Software is required High speed I/O devices are required Sophisticated backup procedure is required

Objectives of Database System There should be centralized control Redundancy should be avoided Inconsistency should be avoided System should be easy to use Standards should be enforced Data should be sharable

Objectives Contd. . Conflicting requirements should be balanced User’s requirements should be fulfilled Security should be provided Privacy should be provided Data Independence should be there

Points to think…… Difference between Database & Database System Difference between Advantages & Objectives

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