Department of Information Technology
Digital notes
On
database
management system
Faikate Public School
,UNIT-ONE
Introduction to Database Management System
As the name suggests, the database management system consists of two parts. They are:
1. Databaseand
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. 01, ABC, 19 etc).
Record: Collection of related data items, e.g. in the above example the three data items had no
meaning. However, if we organize them in the following way, then they collectively represent
meaningful information.
Roll Name Age
01 ABC 19
Table or Relation: Collection of related records.
Roll Name Age
01 ABC 19
02 DEF 22
03 XYZ 28
The columns of this relation are calledFieldsAttributes
, or Domains.
The rows are called Tuples or Records.
Database: Collection of related relations.
Consider the following collection of tables:
T1 T2
Roll Name Age Roll Address T3
01 ABC 19 01 KOL Roll Year
DEL 01 I
02 DEF 22 02
02 II
03 XYZ 28 03 MUM
03 I
, T4
Year Hostel
I H1
II H2
We now have a collection of four tables. They can be called a “related collection” because we can
clearly find out that there are some common attributes existing in a selected pair of tables. Because
of these common attributes, we may combine the data of two or more tables together to find out the
complete details of a student.
Questions like “Which hostel does the youngest student live in?” can be answered now, although
Age and Hostel attributes are in different tables.
A database in a DBMS could be viewed by lots of different people with different responsibilities.
Figure 1.1: Employees are accessing Data through DBMS
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 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.
The management system is important, why? Because without the existence of some kind of
rules and
regulations it is not possible to maintain the database. We have to select the particular
attributes, which
should be included in a particular table; the common attributes to create relationship
between two
tables; if a new record has to be inserted or deleted then which tables should have to be
handled etc. These issues must be resolved by having some kind of rules to follow in order to
maintain the integrity of the database. Database systems are designed to manage large
mechanisms for the manipulation of information.
bodies of information. Management of data involves both defining structures for storage of
In addition, the database system must ensure the safety of the information stored, despite
information and providing
system crashes or attempts at unauthorized access. If data are to be shared among
several users, the system must avoid possible anomalous results. Because information is
so important in most organizations, computer scientists have developed a large body of
concepts and techniques for managing data. This chapter briefly introduces the principles
of
database systems.
Database Management System (DBMS) and Its Applications:
A Database management system is a computerized record-keeping system. It is a
repository or a container for collection of computerized data files. The overall purpose of
DBMS is to allow the users to define, store, retrieve and update the information contained in
the database on demand. Information can be anything that is of significance to an individual
or organization.
Databases touch all aspects of our lives. Some of the major areas of application are as follows:
Digital notes
On
database
management system
Faikate Public School
,UNIT-ONE
Introduction to Database Management System
As the name suggests, the database management system consists of two parts. They are:
1. Databaseand
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. 01, ABC, 19 etc).
Record: Collection of related data items, e.g. in the above example the three data items had no
meaning. However, if we organize them in the following way, then they collectively represent
meaningful information.
Roll Name Age
01 ABC 19
Table or Relation: Collection of related records.
Roll Name Age
01 ABC 19
02 DEF 22
03 XYZ 28
The columns of this relation are calledFieldsAttributes
, or Domains.
The rows are called Tuples or Records.
Database: Collection of related relations.
Consider the following collection of tables:
T1 T2
Roll Name Age Roll Address T3
01 ABC 19 01 KOL Roll Year
DEL 01 I
02 DEF 22 02
02 II
03 XYZ 28 03 MUM
03 I
, T4
Year Hostel
I H1
II H2
We now have a collection of four tables. They can be called a “related collection” because we can
clearly find out that there are some common attributes existing in a selected pair of tables. Because
of these common attributes, we may combine the data of two or more tables together to find out the
complete details of a student.
Questions like “Which hostel does the youngest student live in?” can be answered now, although
Age and Hostel attributes are in different tables.
A database in a DBMS could be viewed by lots of different people with different responsibilities.
Figure 1.1: Employees are accessing Data through DBMS
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 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.
The management system is important, why? Because without the existence of some kind of
rules and
regulations it is not possible to maintain the database. We have to select the particular
attributes, which
should be included in a particular table; the common attributes to create relationship
between two
tables; if a new record has to be inserted or deleted then which tables should have to be
handled etc. These issues must be resolved by having some kind of rules to follow in order to
maintain the integrity of the database. Database systems are designed to manage large
mechanisms for the manipulation of information.
bodies of information. Management of data involves both defining structures for storage of
In addition, the database system must ensure the safety of the information stored, despite
information and providing
system crashes or attempts at unauthorized access. If data are to be shared among
several users, the system must avoid possible anomalous results. Because information is
so important in most organizations, computer scientists have developed a large body of
concepts and techniques for managing data. This chapter briefly introduces the principles
of
database systems.
Database Management System (DBMS) and Its Applications:
A Database management system is a computerized record-keeping system. It is a
repository or a container for collection of computerized data files. The overall purpose of
DBMS is to allow the users to define, store, retrieve and update the information contained in
the database on demand. Information can be anything that is of significance to an individual
or organization.
Databases touch all aspects of our lives. Some of the major areas of application are as follows:
