Page 233 - PYTHON-12

A DBMS stores data in such a manner that it becomes
easier and highly efficient to retrieve, manipulate and
produce information. Thus, a DBMS is an electronic
or computerized record-keeping system. It maintains
the various pieces of information in an integrated and
summarized form instead of keeping them in separate
independent files.
Examples of Database Management Systems are
MS Access, MySQL, PostgreSQL, SQLite, Microsoft SQL
Server, Oracle, SAP, dBase, FoxPro, etc.

Few customized DBMSs are computerized library
systems, automated teller machines, flight reservation Fig. 12.4: Role of Database Management System
systems, computerized parts, inventory systems, etc.
A DBMS gives us tools to:

 Store data in a structured way.
 Query the database (i.e., ask questions about the data).

 Sort and manipulate the data in the database.
 Validate the data entered and check for inconsistencies.
 Produce flexible reports, both on screen and on paper, that make it easy to comprehend the
information stored in the database.

Also, it maintains data consistency in the case of multiple users.
CTM: A DBMS is a general purpose software system that facilitates the process of defining, constructing and
manipulating databases for various applications.

12.2.1 Need for DBMS

The database system is used to eliminate the problems of data redundancy and data inconsistency.
It does not maintain separate files for different applications. Rather, it works on the centrally
maintained database, which means that the data is kept at one place and all the applications that
require the data may refer to this database. Whenever any file gets updated, the updated version
of the file is available to all applications using the database system, as shown in Fig. 12.5. So, data
redundancy and data inconsistency are controlled to a large extent.
However, at times, there might be data redundancy due to some technical requirements in business
applications. In such cases, we are required to maintain same data for different files but this is not
recommended.
Relational Database and SQL

Fig. 12.5: Purpose of a Centralized Database System
12.3