CBSE Guess > Papers > Important Questions > Class XII > 2013 > Multimedia & Web Technology > Multimedia & Web Technology - by Mr. Amrit Chhetri
CBSE CLASS XII
Multimedia & Web Technology
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:
- CUST_ID
- BOB_ID
- PAN_NUMBER
- AADHAR_NUMBER
- 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:
- It reduces the redundancy of data.
- It gives a distributed data management system.
- It avoids the inconsistency of data.
- It maintains the data integrity.
DBMS are provided by the product companies like Oracle and two example of FOSS DBMS are:
- MySQL Database
- 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 |
- Name the field, which can act as the primary key for the table BOOK_INVENTORY and the table BOOK_SALES respectively.
- Name the field, which can act as the foreign key for the table BOOK_SALES.
- 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:-
- One-To-One
- One-To-Many
Submitted By : Mr. Amrit Chhetri
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