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UNIT 2
DATABASE MANAGEMENT SYSTEMS
A
Discussion Starter
What is a database? What does it consist of?
What parameters are considered while classifying a database system? Identify some basic
database classifications and discuss their differences.
What are the characteristics of cloud databases?
How is a relational database designed, used and maintained?
Comment on the pictures given below.
A
B
C
D
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B
Before You Read
Read the title from the article below.
What aspects do you think the text is going to highlight?
Who is involved with a database management system (DBMS)?
C
Read the Article
Database Management Systems
To the computer, a database looks like one or more files.
In order
for the data in the database to be read, changed, added, or removed,
a software program must access it. Many software applications
have this ability: iTunes can read its database to give you a listing
of its songs (and play the songs); your mobile-phone software can
interact with your list of contacts.
But what about applications to create or manage a database? What
software can you use to create a database, change a database’s
structure, or simply do analysis? That is the purpose of a category of software
applications called
database management systems (DBMS).
A DBMS makes it possible for end users to create, read, update and delete data in a database. The
DBMS essentially serves as an interface between the database and end users or application
programs, ensuring that data is consistently organized and remains easily accessible. The DBMS
manages three important things:
the data, the database engine that allows data to be accessed,
locked and modified - and the database schema, which defines the database’s logical structure.
These three foundational elements
help provide concurrency, security, data integrity and uniform
administration procedures. Typical database administration tasks supported
by the DBMS include
change management, performance monitoring/tuning and backup and recovery. Many database
management systems are also responsible for automated rollbacks, restarts and recovery as well as
the logging and auditing of activity.
A key component of a DBMS is the database engine – the part of the program that actually stores
and retrieves data. In addition to a database engine, most DBMSs come bundled with a set of tools
to perform a variety of necessary tasks, such as creating forms (used to input data) and reports (used
to output data), and interfacing with query languages and programming
languages for complex
applications. Programming languages typically used with databases today include Visual Basic,
Java, and C++, although many older legacy database systems still use COBOL.
DBMS packages generally provide an interface to view and change the design of the database,
create queries, and develop reports. Most of these packages are designed
to work with a specific
type of database, but generally are compatible with a wide range of databases.
For example, Apache OpenOffice.org Base can be used to create, modify, and analyze databases in
open-database (ODB) format. Microsoft’s Access DBMS is used to work with databases in its own
Microsoft Access Database format. Both Access and Base have the ability to read and write to other
database formats as well.
Microsoft Access and Open Office Base are examples of personal database-management systems.
These systems are primarily used to develop and analyze single-user databases. These databases are
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not meant to be shared across a network or the Internet, but are instead
installed on a particular
device and work with a single user at a time.
DBMSs are designed for a variety of environments. Some are designed to be single-user systems,
while others are designed for medium-sized businesses, while still others are designed for large
businesses.
