PM system
INTRODUCTION TO DATABASES
A collected information which is in an organized
form for easier access, management, and various updating
is known as a database. Database Management System or
DBMS must have some means of representing the data in
a way that user can easily understand. A DBMS provides
users with the conceptual representation of data.The
system hides certain details regarding data storage and
maintenance and data is retrieved efficiently.
File System Vs. DBMS
A comparison between a file processing system
and a DBMS is given below:
DBMS File Processing System
It is a shared set ofdata that is
logicallyrelated. It describes the data It is a set of application
designed tomeet the information programs that serves the end –
requirements of an organization users in various ways, such as
by producing reports. Each
program defines and manages
its own data.
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PM system
Redundancies and inconsistencies in Redundancies and
data are reduce due to single file inconsistencies in dataexist due to
formats and duplication of data is single file formats and duplication
eliminated
Data is easily accessed due to Data cannot be easily
standard query procedures. accessed due to special
application programsneeded
to access data.
Isolation / retrieval ofthe required
data is possible due to common Data isolation is difficultdue to
file format and there areprovisions different fileformats and also
to retrieve data easily becausenew application
programs have to be written.
It provides programand data
There is a dependency between
independence.
application programs and data.
This is because, definition of
data is embedded in the
application program rather than
stored separately.
Integrity constraints, whether new or Introduction of integrity
old, can be enforced as per need. constraints is tedious and new
Data integrity is determined on the application programs have to be
data itself written in order to determine
data integrity in each
application
Atomicity of updates ispossible.
Atomicity of updatesmay not be
maintained.
Several users can access data at the Concurrent accesses maycause
same time, ie, concurrently without problems, such as
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PM system
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