• +91 9971497814
  • info@interviewmaterial.com

Chapter 11- Database Concepts Interview Questions Answers

Question 1 :
What is relation? Define the relational data model.

Answer 1 :

A relation is a table having atomic values, unique row and unordered rows and columns. The relational mode represent data and relationship among data by a collection of tables known as relation, each of which has a number of columns with unique names.

Question 2 :
What are all the domain names possible in gender ?

Answer 2 :

Male and Female.

Question 3 :
Give a suitable example of a table with sample data and illustrate Primary and Candidate Keys in it.

Answer 3 :

A table may have more than one such attribute/ group of attribute that identifies a row/tuple uniquely, all such attribute(s) are known as Candidate Keys. Out of the Candidate keys, one is selected as Primary Key,

Question 4 :
Observe the following table carefully and write the names of the most appropriate columns, which can be considered as (i) candidate keys and (ii) primary key.

Answer 4 :

Candidate keys : Id, Product
Primary keys: Id

Question 5 : Observe the following table carefully and write the names of the most appropriate columns, which can be considered as (i) candidate keys and (ii) primary key :

Answer 5 :

Candidate keys : Code, Item Primary keys : Code

Question 6 : Define degree and cardinality. Based upon given table write degree and cardinality.

Answer 6 :

Degree is the number of attributes or columns present in a table.
Cardinality is the number of tuples or rows present in a table.
Patients Degree = 4
Cardinality = 5

Question 7 :
Differentiate between the Primary key and Alternate key of a table with the help of an example.

Answer 7 :

Primary Key – A primary key is a value that can be used to identify a unique row in a table .
Alternate Key – An alternate key is any candidate key which is not selected to be the primary key.
Example:
 
So, (Bank Account Number, Aadhaar Number) is a candidate key for the table.
Aadhaar Number ” Primary key
Bank Account Number ” Alternate Key

Question 8 :
Explain the concept of candidate keys with the help of an appropriate example.

Answer 8 :

Candidate key is a column or set of columns that can help in identifying records uniquely.
Example,consider a Table STUDENT
 
Here, AdminN0  & Roll N0 define Table uniquely.
Hence, they are candidate keys.

Question 9 :
A table ‘customer’ has 10 columns but no row. Later, 10 new rows are inserted and 3 rows are deleted in the table. What is the degree and cardinality of the table customer

Answer 9 :

Degree = 10[no.of cols]
Cardinality = 10-3=7[no.of rows]

Question 10 :
A table ‘student’ has 3 columns and 10 rows and another table ‘student 2’ has the same number of columns and 15 rows. 5 rows are common in both the tables. If we take union, what is the degree and cardinality of the resultant table ?

Answer 10 :

Degree-3
Cardinality – 30 = (20 + 15-5)


Selected

 

Chapter 11- Database Concepts Contributors

krishan

Share your email for latest updates

Name:
Email:

Our partners