404 Chapter 8: Databases
database system contains not only data but it describes
the description of the database structure.
8.1.2 Database Management System
A database is a collection of related data. Data is a collection of raw facts or figures, processed to form information. Database management system is a collection of
programs for the creation and maintenance of database.
It is an efficient and reliable approach to retrieve data
for many users. It provides various functions such as:
1. Redundancy control: It provides redundancy
by removing duplicity of data by following rules of
2. Data independence: It provides independence
to application programs from details of data representation and storage. It also provides an abstract
view of the data to insulate application code from
3. Data integrity: It promotes and enforces some
integrity rules for reducing data redundancy and
increasing data consistency.
4. Concurrency control: It supports sharing of
data, so, it has to provide an approach for managing
concurrent access of the database. Hence, preserving the inconsistent state and integrity of the data.
5. Transaction management: It provides an
approach to ensure that either all the updates for a
given transaction will execute or that none of them
6. Backup and recovery: It provides mechanisms
for backing up data periodically and recovering
from different types of failures, thus, preventing
loss of data.
7. Non-Procedural query language: It provides
with query language for retrieval and manipulation
8. Security: It protects unauthorized access in the
database. It ensures the access to authorized users.
8.2 COMPONENTS OF DATABASE
DBMS consists of several components, namely software,
hardware, data, procedures and data access language.
These components are responsible for the definition, collection, management and use of data within the environment. Figure 8.1 shows the components of database
system. The description of each component is as follows:
1. Software: It is the collection of programs used
by the computers within the database system. It is
used to handle, control and manage the database.
It includes the following software:
Chapter 8.indd 404
system software like Microsoft Windows, Linux OS, Mac OS.
••DBMS software such as Oracle 8I, MySQL,
Access (Jet, MSDE), SQL Server etc.
••Network softwares are used for sharing share the
data of database among multiple users.
••Application programs are developed like C++,
VB, dotnet etc. are used to access database in
dbms. These are used to access and manipulate
the data in the database.
2. Hardware: It consists of all system’s physical
devices such as computers, storage devices, I/O
channels, electromechanical devices etc. It also
includes peripherals, such as, keyboard, mouse,
modems, printers, etc.
3. Data: It is the collection of facts. The database
contains the data and the metadata.
4. Procedures: There are the instructions and rules
to design and use the database system. These
includes the following:
for the installation of DBMS
to use the DBMS or application program
••Steps for the backup of DBMS
••Steps to change the structure of DBMS
••Steps for the generation of reports.
5. Data access language: The users can use it to
access the data to and from the database. The function of data access language is the entry of new data,
manipulation of the existing data and the retrieval of
the existing data in the database. The most popular
database access language is SQL (Structured Query
Language). Users can perform these functions with
the help of commands. The role of administrator is
to access, to create and to maintain the database.
6. People: Persons involved to access, to create and
to maintain the database are called users. These
are of various types according to the role performed
by them (Fig. 8.1). These are as follows:
Administrator: The role of system
a dministrator is to supervise the general operations of DBMS.
••Database Administrator: The role of database
administrator (DBA) is to manage the DBMS.
••Database Designer: The role of database
designer is to design the structure of the database.
••Application Programmer: The role of
application programmer is to create the data
entry forms, reports and procedures.
••End User: The role of end user is to use the
application programs by entering new data and
manipulating and accessing existing data.
4/9/2015 10:03:29 AM