2. INTRODUCTION
A database can be defined as the collection of information organized
in an efficient way so that the computer program can quickly retrieve
the data.
It is a collection of the data elements which shows the real world
information
It should be logical, coherent and internally consistent.
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3. COMPONENTS OF DATABASE
A database system is composed of mainly four components.
The people who manages the database.
The hardware which consists of various secondary devices such as
magnetic tapes, hard disks, floppy disks , etc.
A software which is the most important component of database and
it also acts as the interface between user and the database.
And the data, an important component of database.
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4. DATABASE MANAGEMENT
SYSTEM
It is a software that enables users to define , create, and maintain the
database and also provides controlled access to the database.
The main purpose of a database ,management system is to bridge the
gap between information and data.
The data stored in the memory must be converted to usable
information.
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5. PROCESSES SUPPORTED
•Specification of data types, structures and constraints that are to be
included in an application.
•Keeping the data into a persistent storage.
•Manipulation of the data.
•Querying the database for the retrieval of desired information.
•Updating the content of database.
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7. ADVANTAGES OF DBMS
Centralised nature of database system provides several advantages:
•Reduced data redundancy.
•Elimination of inconsistency.
•Data sharing.
•Data security.
•Data integrity.
•Backup and recovery.
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8. LIMITATIONS OF DBMS
Data quality:-
With the increase in the number of users which are accessing the data,
there are strong chances for users to damage the data.
Privacy and security:-
As information is made available to the users from the remote
locations, the possibilities of abuse are often more than the traditional
file systems.
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9. LIMITATIONS OF DBMS
A database system generally provides online access and information
for many users but it have some limitations:
High cost DBMS:-
It requires various software, hardware and highly intelligent people
for operation and maintaining database system.
Database failure:-
All data is integrated into single system. If database is corrupted then
our data may be lost.
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10. VIEWS OF DATA
A major purpose of the database system is to provide users with an
abstract view of data.
The system hides certain details of how the data are stored and
maintained. As the users are not always computer trained, so the
developers hide the complexity from the users through several levels
of abstraction.
The concept is also called as Data abstraction.
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12. LEVELS OF ABSTRACTION
Internal level:-
It is the lowest level of abstraction that describes how the data is
physically stored and organised on the storage medium. It is also
called as the physical level.
Conceptual level:-
It provides the logical view to entire database as it describes what data
is stored in the database.
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13. LEVELS OF ABSTRACTION
External level:-
It is the highest level of database abstraction and also known as the
view level. It describes the part of database for a particular group of
users.
As in general, most of the users do not require the entire database,
instead , they need to access only a part of database.
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