DATABASE CONCEPTS

INTRODUCTION

A database system is basically a computer based record  keeping system. the collection of the data, usually refered to as the database, contains information about one particular enterprise. it maintains any information that may be necessary to the decision making processes involved in the management  of that organization.

A database may also be defined as a collection of interrelated data stored together to serve multiple applications; the data is such stored so that it is independent of programs which use the data; a common and controlled approach is used in adding new data and in modifying and retrieving existing data within the database.The data is structured so as to provide a foundation for future application development.

Database system

The intention of a database is that the same collection of data should serve as many applications as possible. hence, a database is often conceived of as the repository of information needed for running certain functions in a corporation or orgainzation. such a database would permit not only the retrieval of data but also the continuous modification of data needed for control of operations. it may be possible to search the database to obtain answer to queries or information for planning purposes.

PURPOSE OF DATABASE

In a typical file-processing system, permanent records are stored in various files.A number of different application programs are written to extract records from and add records to the appropriate files.But this scheme has a number of major limitations and disadvantages, such as data redundancy, data inconsistancy, unsharable data, understandized data, insecure data, incorrect data etc. A database management system is answer to all these problems as it provides a centralized control of the data.

Let us consider some of the advantage provided by the database system and see how a database system overcomes the mentioned problems.

1. DATABASE REDUCE THE DATA REDUNDANCY TO A LARGE EXTENT

Data redundancy means duplication of data. Non database system maintain separate copy of data for each application. e.g., in a college , student records are maintain and the hostal also maintain records of all those students who live in hostal. Though the records for hosteler students are already being maintain by the college, the hostal keeps a separate copy of it. As far as everything goes well, the above mentioned file processing system works well. But duplication of data may lead to inconsistency or incorrect data  at times.

the database system do not maintain separate copies of the same data. rather all the data are kept at one place and all the application that require data refers to the centrally maintain database. Now , if any changes to be made to data, it will be made at just one place and te same changed information will be available to all the applications refering to it. Thus, redundancy gets controlled and so are the problems associated with it.

2. DATABASE CAN CONTROL DATA INCONSISTENCY TO A LARGE EXTENT

This is really a corollary of the previous point. when the redundancy is not controlled where may be occasions on which the two entries about the same data do not agree. at such time data base is said to be inconsistance. obviously, an inconsistance database will provide incorrect or conflicting information

By controlling redundancy, the inconsistancy is also control. Even if there is some redundancy retains in the database due to some technical reasons, the database management system ensures that any change made to either of the two entries is automatically made to the others. This process is known as propagating updates.

3. DATABASE FACILITATES SHARING OF THE DATA

Sharing of data means that individual pieces of data in the database may be shared among several different users, in the sense that each of those user may have access to the same piece of data and each of them may use it for different purpose.

The database management system makes sure that not only the existing application can share the data in the database, but also that new application can be develop to operate against that same stored data, or it can be said that the data requirement of new application may be satisfied without having to create any new stored file.

4. DATABASE ENFORCE STANDARDS

The database management system can ensure that all the data follow the applicable standard. There may be certain standard laid by the company or organization using the database. Or there may be certain industry standard that must be satisfied by the data. Similarly, there may be national or international standards. Standardizing stored data format is particularly desirable as an aid to data interchange or migration between systems.

5. DATABASE CAN ENSURE DATA SECURITY

The information stored inside a database is sometime of great value to a corporation. Therefore, it must be kept secure and private.

A database management system ensures data security and privacy by ensuring that the only means of access to the database is throw the proper channel and also by carrying out authorization checks whenever access to sensitive data is attempted.