Chapter-5 Database Management System

CHAPTER NO.5 DATABASE MANAGEMENT SYSTEM

5.1 INTRODUCTION

In previous classes, we have studied about data and information. We all know that data is similar type of facts or figures and processed form of data is known as information. For example: number '24' may be treated as data, but Age 24, Street No. 24 or Sector 24 is processed form of data which provides some information.

Related information of a particular item may be treated as Record. For example: A student is an item. Student's Name, Roll No., Class, Admission No., etc. is Record of the student.Now, Collection of related record of Number of different students can be treated as File.The Collection of such Files or Tables is known as database.

Now we can understand the hierarchy of Database and can be represented as under:

5.2 DATABASE

The database is a collection of inter-related data which is used to retrieve, insert and delete the data efficiently. It is also used to organize the data in the form of a table, schema, views,

and reports, etc. The basic purpose of database is to combine data from all different sources. So that the useful information available to many users for their different purposes.

5.3 DBMS

DBMSstands for Database Management System. Traditionally, data was organized in file

formats. DBMS is a computerized record keeping system that allows us to electronically organise and manipulate data using computer in a fast and secure way. It allows us to store and maintain data using the software and computer. In simple words, Database management system is software that is used to manage the database. For examples the school Database organizes the data for the admin, staff and students etc,

Examples of some popular DBMS are MySQL, Microsoft Access, dBASE, FoxPro,

Oracle, etc.

DBMS provides an interface to perform various operations like database creation, storing data in it, updating data, creating a table in the database and many more.It provides protectionand security to the database. In the case of multiple users, it also maintains data consistency.

5.4 APPLICATION AREAS OF DBMS

Some of application areas of DBMS are shown in table below:

5.5 DATA BASE LIFE CYCLE

A software development life cycle model (SDLC) consists of a set of processes defined to accomplish the task of developing a software application that is functionally correct and satisfies the user's needs. Various processes in developing any software are:

1. Planing

2. Requirements

3. Design

4, Development

5. Implementation

6. Testing

7. Installation and Maintenance

5.6 DBMS WORKING

A DBMS stores data in a way that it becomes easier to retrieve, manipulate, and produce

information. It is basically a computerized record keeping system.A typical DBMS has users with different rights and permissions who use it for different purposes. Some users retrieve data and some back it up. The users of a DBMS can be broadly

categorized as follows:

Designers - Designers are the group of people who actually work on the designing

part of the database. They keep a close watch on what data should be kept and in

which format. They identify and design the whole set of entities, relations, constraints,and views.

Administrators - Administrators maintain the DBMS and are responsible for

administrating the database, They are responsible to look after its usage and by whom it should be used. They create access profiles for users and apply limitations to

maintain isolation and force security. Administrators also look after DBMS resources like system license, required tools, and other software and hardware related maintenance.

End Users - End users are those who actually reap the benefits of having a DBMS.End users can range from simple viewers who pay attention to the market rates to sophisticated users such as business analysts.

5.7 ARCHITECTURE OF DBMS

Database Management system is composed of many inter-related components. DBMS is

not always directly available for users and applications to access and store data in it. These components are organized to achieve the goals of system, is referred to as architecture of the system. A Database Management system can be centralised (all the data stored at one location),

decentralised (multiple copies of database at different locations) or hiersrchical, depending upon its architecture.

Database system also can be designed in different architectures of a DBMS. The major putpose of this system is to provide users with an abstract view of data. The system hides certain detail of how the data is stored and maintained. The goal of the architecture is to separate the user applications and the physical database.

Database Architecture is of following types:

1. 1-tler DBMS architecture : In this, the database is directly available to the user for using it to store data. Generally such a setup is used for local application development,where programmers communicate directly with the database for quick response.

2. 2-tier DBMS architecture : In 2-tier DBMS architecture, an Application layer is

included in between the user and the DBMS, which is responsible to communicate

the user's request to the database management system and then send the response from the DBMS tc the user.

In the 2-tier architecture, we have an application layer which can be accessed

programmatically to perform various operations on the DBMS. The application

generally understands the Database Access Language and processes end users requests

to the DBMS.An application interface known as ODBC (Open Database Connectivity) provides an API that allows client side program to call the DBMS. Most DBMS vendors provide ODBC drivers for their DBMS.

Such architecture provides the DBMS extra security as it is not exposed to the End

User directly. Also, security can be improved by adding security and authentication checks in the Application layer too.

3. 3-tier DBMS architecture : 3-tier DBMS architecture is the most commonly used

architecture for web applications.

It is an extension of the 2-tier architecture. In 3-tier architecture, an additional Presentation or GUI Layer is added, which provides a graphical user interface for the End user to interact

with the DBMS. For the end user, the GUI layer is the Database System, and the end user has no idea about the application layer and the DBMS system.

5.8 FEATURES/CHARACTERISTICS OF DEMS

If we Compare DBMS to the File Based Data Management System, It has many advantages.

Some of these advantages are given below:

Reducing Data Redundancy : In file-based data management systems, multiple

files were stored at different locations in a system or even across multiple systems.

Multiple copies of the same file leads to data duplicacy or data redundancy. This is

prevented with DBMS as there is a single database and any change in it is reflected

immediately, So, there is no chance of encountering duplicate data,

Sharing of Data : The various users of the database can share the data among

themselves. Here are various levels of authorisation to access the data, and consequently the data can only be shared based on the correct authorisation protocols being followed.Many remote users can also access the database simultaneously and share the data between themselves.

Data Integrity : It means that the data is accurate and consistent in the database.

Data Integrity is very important as there are multiple databases in a DBMS. All of

these databases contain data that is visible to multiple users. So it is necessary to ensure that the data is correct and consistent in all the databases and for all the users,

Data Security : Data Security is very important concept in a database. Only authorised can access the database and their identity should be authenticated using a username and password. Unauthorised users should not be allowed to access the database under any circumstances as it violates the integrity constraints.

Privacy : The privacy in a database means only the authorized users can access a

database according to its privacy constraints. There are levels of database access and a user can only view the data he is allowed to. For example - In social networking sites, access constraints are different for different accounts a user may want to access.

Backup and Recovery : Database Management System automatically takes care of

backup and recovery. The users need not to backup data periodically because this is

taken care of by the DBMS. Moreover, it also restores the database after a crash or

system failure to its previous condition.

Data Consistency : Data consistency is ensured in a database because there is no

data redundancy. All data appears consistently across the database and the data is same for all the users viewing the database. Moreover, any changes made to the

database are immediately reflected to all the users and there is no data inconsistency.

5.9 LIMITATIONS OF DATABASE MANAGEMENT SYSTEM

The following sre the disadvantages of Database Systems

Setup Cost : DBMS requires huge amount of investment, needed to setup the

required hardware and the softwares. High initial investment based upon size and

functionality of organization is required.

Database Complexity : The designing of the database system is complex, difficult

and is very time consuming task to perform, The Developer, designer, DBA and End

user of database must have complete skills, if they don't understand this complex

system then it may cause loss of data or database failure.

‘Technical staff requirement : Initial training is required for organization's employees,all programmers and user. Large amount of human efforts, the time

and cost is needed to train the end users and application programmers in order to get used to the database systems.

Database Failure ; As we know that in DBMS, all the files are stored in single

database so chances of database failure become more. Any accidental failure of

component may cause loss of valuable data. This is really a big question mark for big

firms.

Performance : Traditional files system was very good for small organizations as they

give splendid performance. But DBMS gives poor performance for small scale firms

as its speed is slow.

5.10 CLOUD DATABASE

A cloud database is the database that typically runs on cloud computing platform. Users can choose from two types of methods to run their database in the cloud. The first methed is cloud platforms allow users to install and maintain their own databases for a limited time. That is, users can purchase or maintain a database from a third party and use other services provided

by cloud computing platforms. For example, users can use Oracle Database 11g Enterprise Edition provided by Oracle on Microsoft Azure (which is PaaSPlatform-as-a-service). The second method is cloud platforms are responsible for installing and maintaining the databases

and users pay for these parts of services. This method is called Database-as-a-service (DBaaS)

A database service built and accessed through a cloud platform

Enables enterprise users to host databases without buying dedicated hardware

(Can be managed by the user or offered as a service and managed by a provider

(Can support relational databases and NoSQL databases

Accessed through a web interface or vendor-provided API

Pointseho

1. Related information of a particular item may be treated as Record

2. Collection of related record of Number of different students can be treated as File

3. The Collection of such Files or Tables is known as database

4. The database is a collection of inter-related data which is used to retrieve, insert and delete the data efficiently

5. DBMS stands for Database Management System

6. DBMS is a computerized record keeping system that allows us to electronically organise and manipulate data using computer in a fast and secure way

7. Database management system is software that is used to manage the database.

8. Designers are the group of people who actually work on the designing part of the

database

9. Administrators maintain the DBMS and are responsible for administrating the database.

10, End users are those who actually reap the benefits of having a DBMS

11. In 1-tier DBMS architecture the database is directly available to the user for using it to store data

12. In2-tier DBMS architecture, an Application layer is included in between the user and the DBMS

13. In 3-tier architecture, an additional Presentation or GUI Layer is added, which provides a graphical user interface for the End user to interact with the DBMS

EXERCISE:Part-A

1. Write True or False

1. Collection of related record of Number of different students can be treated as Database.

2 The database is used to retrieve, insert and delete the data efficiently.

3. DBMS is a computerized record keeping system.

4. Database management system is Hardware,

5. Database management system is used to manage the database.

2. Very Short Answer Type Questions

1. Related information of a particular item may be treated as?

2 The Collection of Files or Tables is known as?

3. DBMS stands for?

4. Who are the group of people who actually work on the designing part of the