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PROGRAM - BCA
(Revised Fall 2012)
SEMESTER - 3
SUBJECT CODE &
NAME
BCA3020 – Data Base
Management System(DBMS)
CREDIT - 4
BK ID - B1479
MAX. MARKS – 60
Q1. List and
explain the important responsibilities of database manager. [10]
Ans:
Important responsibilities of database manager: important responsibilities of
Database manager:
·
Interaction
with file manager: The
raw data is stored on the disk using the file system which is usually provided
by a conventional operating system. The database manager translates the various
DML statements into low-level file system commands. Thus the database manager
is responsible for the actual
Q2. What is a table
in relational data model? List the properties of relational tables. [10]
Ans: Relational Data Model: The relational model today, is
the primary data model for commercial dataprocessing applications. It
has attained its primary position because of its
simplicity, which eases the job
of the programmer, as compared to earlier data models such as the network model
or the
Q3. What is data independence?
Briefly explain. [10]
Ans: Data Independence: Data independence is usually
considered from two points of view: physical data independence and logical
data independence. Physical data independence allows changes in the
physical storage devices or organization of the files to be made without
requiring changes in the conceptual view or any of the external views
and hence in the application programs using the database. Thus, the
files may migrate from one type of physical media to another or the file
structure may change without any need for changes in
Q5. What is view?
List its advantages. [4+6]= 10
Ans:
Views: A view is a virtual table which
does not actually exist. It is made up of a query on other tables in the
database. It could include only certain columns or rows from a table or
from many tables. A view which restricts the user to certain rows is
called a horizontal view, and a vertical view restricts the user to
certain columns. You are not restricted to purely horizontal or vertical slices
of data. A view can be as complicated as you like. You can have grouped
views,
where the query contains a GROUP
BY clause. This makes the view a summary of the data in a table or tables. A
view is a relation (virtual other than base) and can be used in query expressions,
that is, queries can be written using
Q6. Write a note on
the following: 5+5
a) SUBSET Mapping
b) SUPERSET Mapping
Ans: We can see that classes of OOP language can be
mapped to RDBMS tables. For e.g. JAVA classes can be mapped to RDBMS tables. We
can map a persistent class and a table in so many ways. The simplest mapping
between a persistent class and a table is one-to-one. In this case, all
attributes in the persistent class are represented by all columns of a table.
Each instance of a business class is then stored in a row of the table.
Get fully solved assignment. Buy
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we will revert you within 2-3
hour or immediate
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