Introduction to Database Management Systems

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DBMS View

Introduction to Database Management Systems

As the name suggests, the database management system(DBMS) consists of two parts. They are:
1. Database and
2. Management System

What is a Database?

To find out what database is, we have to start from data, which is the basic building block of any DBMS.

Data: Facts, figures, statistics, etc. having no particular meaning (e.g. 1, John, 19, etc).

Record: Collection of related data items, e.g. in the above example the three data items had no meaning. But if we organize them in the following way, then they collectively represent meaningful information.

RollNameAge
1John19

Table or Relation: Collection of related records.

RollNameAge
1John19
2Rocky22
3Smith28

The columns of this relation are called Fields, Attributes or Domains. The rows are called Tuples or Records.
Database: Collection of related relations. Consider the following collection of tables:

List 1 (T1)

 

Roll

 

Name

 

Age

 

1

 

John

 

19

 

2

 

Rocky

 

22

 

3

 

XYZ

 

28

List 2 – T2

 

Roll

 

Address

 

1

 

Canada

 

2

 

Australia

 

3

 

INDIA

List 3 – T3

 

Roll

 

Year

 

1

 

I

 

2

 

II

 

3

 

I

List 4 – (T4)

 

Year

 

PLACE

 

I

 

H1

 

II

 

H2

A database in a DBMS could be viewed by lots of different people with different responsibilities.

DBMS View

For example, within a company, there are different departments, as well as customers, who each need to see different kinds of data. Each employee in the company will have different levels of access to the database with their own customized front-end application.

In a database, data is organized strictly in a row and column format. The rows are called Tuple or Record. The data items within one row may belong to different data types. On the other hand, the columns are often called Domain or Attribute. All the data items within a single attribute are of the same data type.

What is Management System?

 A database-management system (DBMS) is a collection of interrelated data and a set of programs to access those data. This is a collection of related data with an implicit meaning and hence is a database. The collection of data, usually referred to as the database, contains information relevant to an

enterprise. The primary goal of a DBMS is to provide a way to store and retrieve database information that is both convenient and efficient. By data, we mean known facts that can be recorded and that have implicit meaning.

Database systems are designed to manage large bodies of information. Management of data involves both defining structures for the storage of information and providing mechanisms for the manipulation of information. In addition, the database system must ensure the safety of the information stored, despite system crashes or attempts at unauthorized access. If data are to be shared among several users, the system must avoid possible anomalous results.