DBMS

(DATABASE MANAGEMENT SYSTEM)

DATABASE It is a collection of files that are linked in such

way that information from one of the files may be combined with information of other files so that user may receive the exact information needed.

A database is any organized collection of data. Some examples of databases you may encounter in your daily life are:

• a telephone book

• T.V. Guide

• airline reservation system

• motor vehicle registration records

• papers in your filing cabinet

• files on your computer hard drive.

DBMS

• Is a collection of related information so that it is available to many users for different purposes. The content of database is obtained by combining the data from different sources in an organization.

• Technically speaking, it is a software system that uses a standard method of cataloging, retrieving, and running queries on data. The DBMS manages incoming data, organizes it, and provides ways for the data to be modified or extracted by users or other programs.

• Some DBMS examples include MySQL, Microsoft Access, SQL Server, Oracle, RDBMS, dBASE, and FoxPro. Since there are so many database management systems available, it is important for there to be a way for them to communicate with each other.

• ORGANIZATION :-

A company, business, firm, or association.

• ENTERPRISE :-

An enterprise is any kind of organization such as bank, a university, a manufacturing plant or hospital.

DATA

It is a collection of related information or is used to assert meaningfull information.

OR

Data can be defined as representation of facts,concepts or instructions in a formalized manner suitable for communication,interpretation or processing by human or electronic machine.Data is represented with the help of characters like Alphabets(A-Z), digits(0-9), special characters(+.-,/,<,>,= etc).

• Information :- It is the processed form of data on which decisions & actions are based.For the decision to be meaningful,the processed data must qualify for the following features:-

• Timely

• Accurate

• Complete

• Given to the right person

• Example :- Marks obtained in different subjects in a particular examination of a student act as data.By processing this data, result may be obtained.The result is the information, teacher uses to declare a student pass or fail.

Characteristics/Qualities of Information

• 1) Accuracy :- Information, If it is to be of value,should be accurate & should truly reflect the situation or behavior of an event as it really is.

• 2) Relevance:- It refers to current utility of information in decision making or problem solving. Thus,information gains value if it is relevant.

• 3) Timeliness: It means that information should be made available when it is needed for a particular purpose & not before & in any case not after.

• 4) Completeness:- Information is considered as complete if it tells its user all what he wishes to know about a particular situation/problem.The more than completeness of information,the higher is its value.

• 5) Purpose:- Information must have purpose at the time it is transmitted to a person or machine,otherwise it is simply data.

• 6) Reliability:- The information should be reliable & external force relied upon indicated.

• 7) Validity:- It measures the closeness of the information to the purpose.

NEED OF INFORMATION • It is useful for making decisions.

• It helps managers(or users) in lowering the level of uncertainities where they have to make a choice among several available alternatives.

• It helps the user in trackling problems relating to their respective functional areas.

• It is used by top management to plan the objectives of the organization & to access whether the objectives are being met in practice.

Data vs. information What is the difference?

What is data? What is information?

• Data can be

defined in many ways. Information science defines data as unprocessed information.

• Information is data that have been organized and communicated in a coherent and meaningful manner.

• Data is converted into information, and information is converted into knowledge.

• Knowledge; information evaluated and organized so that it can be used purposefully.

Why do we need a database?

•Keep records of our:

• Clients

• Staff

• Volunteers

•To keep a record of activities

•Keep sales records;

•Develop reports;

• Perform research

•Longitudinal tracking

What is the ultimate purpose of a database management system?

Is to transform

Data Information Knowledge Action

FILE (DATA FILE) File is a collection of related record. E.g –

Payroll file might consist of the employee pay record for a company.

• E.g :- Consider the STUDENT file DATA ITEM RECORD

STUDENT : FILE

• RECORD

ROLL NO NAME MARKS

1002 RITU 75

1003 AMAN 50

AMIT 1001 85

MARKS

DATA ITEM

• A set of characters which are used together to represent a specific data element. E. g – name of student in a class is represented by the data item, say - NAME.

OR

• An individual item in a record is called Data Item.

There are two types of Data Item depending upon the usage are as follow:-

1) Elementary Data Item:-’

These data item can not be further sub-divided. For eg – Roll No

2) Group Data Item:-

These can be further sub-divided into elementary data item. For Eg- Date. Date may be divided into Days, Months,Years.

TYPES OF FILE Types of files are classified into 2

1) According to the FUNCTION

2) According to the MODE OF ACCESS

Types of files (Acc. To Function)

1) MASTER FILE :- It contain data which is required during each processing cycle & needs to ne retained permanently. For eg – The file containing data for the railway reservation/cancellation.

2) TRANSACTION FILE :- Changes which are applied to a master file are collected on a transaction file.

3) REPORT FILE :- Contain data that are formatted for presentation to a user.e.g – pay slip,electrictity bill are the report file.

4) WORK FILE :- It is the temporary file in the system.These files are created during the processing for storing some intermediate data & are deleted after the processing is over.

5) PROGRAM FILE :- It contain instruction for the processing of data.Instruction may be in the form of source code written in programming language like Pascal, C,C++ Etc.

6) TEXT FILE :- Contains numeric & graphic data input using a text editor program.

7) BACKUP FILE:- It is used to store a duplicate copy of the data or program files on secondary storage device like Magnetic Tape or Disk.

Types of files ( Acc. to Mode of Access) 1) INPUT FILE :- Input file is only read by a program.For Eg – A file of tax rates would be an input files for the program that computes income taxes. The transaction file is generally input file to an update program.

2) OUTPUT FILE :- output is created by the program. Eg – report file may be output of a program that updates a master file.

3) INPUT/OUTPUT :- I/O files are both read from & written to during a program execution. E.g – A payroll master file might be used by a payroll program both as a source of data about employees pay rate & as a report for month to date & year to date pay totals. A master file is commonly an I/O files