CBSE Important Questions

CBSE Guess > Papers > Important Questions > Class XII > 2013 > Multimedia & Web Technology > Multimedia & Web Technology - by Mr. Amrit Chhetri

CBSE CLASS XII

Multimedia & Web Technology

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Q. 11. What is importance of Primary Key? Explain with a suitable example.

ANSWER-Q1.11:
A Primary Key of relation identifies the unique records in the relation. The relation is also called Table. A Primary Key is a set of one or more than one attributes in a table. No two values of  in a table have same values if the column is Primary Key. A table can have multiple Candidate Keys but at most one Primary Key. A Primary Key column can't accept the duplicate values.
Let's consider a table named CUSTOMER_DETAILS consists of the following attributes:

  1. CUST_ID
  2. BOB_ID
  3. PAN_NUMBER
  4. AADHAR_NUMBER
  5. CUST_NAME

Any one out of CUST_ID, BOD_UD , PAN_NUNBER and AADHAR_NUMBER can be used as the Primary Key and the remaining columns are called as Alternate Keys.

Q. 12. Write a short notes on DBMS. 

ANSWER-Q1.12:
DBMS is a Software System that stores data in a tabular form. It is the software system that stores data, table, views and other database objects as tables. All system level information stored inside the special storage area and that is called Data Dictionary. Database Management System adds some significances and the important significances are:

  1. It reduces the redundancy of data.
  2. It gives a distributed data management system.
  3. It avoids the inconsistency of data.
  4. It maintains the data integrity.

DBMS are provided by the product companies like Oracle and two example of FOSS DBMS are:

  1. MySQL Database
  2. Postgresql Database

Q. 13. Study the following-data and answer the questions given below : 

Table: BOOK_INVENTORY

TITLE_ID TITLE AUTHOR PUB_YEAR MRP
2310201201 Revolution 2020 Chetan Bhagat 2011 140.00
2410201202 The Facebook Effect D. Kirkpatrickt 2010 399.00
2110201203 The Grand Design S Hawking 2010 499.00
2110201204 Wine Collin Gem 2009 320.00

Table: BOOK_SALES

TITLE_ID ISBN_NO SALE_DATE DIS_PRICE
2310201201 978-81-291-1880-1 23/10/2012  120.00
2310201201 978-81-291-1880-2 24/10/2012  120.00
2110201203 978-81-291-1882-1 21/10/2010 450.00
2410201204 978-81-291-1883-1 12/10/2010 220.00
  1. Name the field, which can act as the primary key for the table BOOK_INVENTORY and the table BOOK_SALES respectively.
  2. Name the field, which can act as the foreign key for the table BOOK_SALES.
  3. What kind of relations can exist between BOOK_INVENTORY and BOOK_SALES?

ANSWER-Q1.13.1:
TITLE_ID can act as Primary Key for BOOK_INVENTORY table.

ANSWER-Q1.13.2:
TITLE_ID is the Foreign Key for BOOK_SLAES table.

ANSWER-Q1.13.1:
Two types of relations can between them and they are:-

  1. One-To-One
  2. One-To-Many

 

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Submitted By : Mr. Amrit Chhetri
Computer Science Trainer/Educator, Principal Business Consultant, Social Media Strategist
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