Quark Placement Paper -: SQL Questions With Answers

Quark Previous Years Solved Sample Placement Papers

1. Q1) What are the constraints and give examples that include all constraints?
   Constraints are rules that limit the values that can be inserted into a database table.
   Examples of constraints include:
   
   • Primary Key
   • Foreign Key
   • Unique
   • Check
   • Not Null
   Basic SQL queries include SELECT, INSERT, UPDATE, and DELETE statements.
   College project questions may vary depending on the project and interviewer.
   

   A. Constraints only

   B. SQL queries only

   C. Both constraints and SQL queries Answer: Option C

   D. Neither

2. Q2) What is normalization? What is a subquery? What is performance optimization?
   Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.
   A subquery is a query nested within another query.
   Performance optimization involves improving the efficiency of a system.
   

   A. Normalization only

   B. Subquery only

   C. Performance optimization only

   D. All of the above Answer: Option D

3. Q3) Difference between various SQL joins?
   SQL joins are used to combine data from two or more tables based on a related column.
   
   • INNER JOIN: Returns only the matching rows from both tables.
   • LEFT JOIN: Returns all rows from the left table and matching rows from the right table.
   • RIGHT JOIN: Returns all rows from the right table and matching rows from the left table.
   • FULL OUTER JOIN: Returns all rows from both tables, with NULL values where there is no match.
   • CROSS JOIN: Returns the Cartesian product of both tables.

   A. INNER JOIN

   B. FULL OUTER JOIN

   C. CROSS JOIN

   D. All of the above Answer: Option D

4. Q4) What are the OOPs concepts in Java?
   OOPs concepts in Java refer to Object-Oriented Programming principles:
   
   • Inheritance: Allows a class to inherit properties and behavior from another class.
   • Polymorphism: Ability of an object to take on multiple forms.
   • Encapsulation: Bundling of data with methods that operate on that data.
   • Abstraction: Hiding the implementation details and showing only the necessary features.

   A. Inheritance

   B. Encapsulation

   C. Abstraction

   D. All of the above Answer: Option D

5. Q5) Write a program to reverse a string.
   Steps:
   
   • Iterate through each string in the array.
   • Reverse each string using built-in functions or manual reversal.
   • Store the reversed strings back in the array.

   A. Iterate only

   B. Reverse only

   C. Store only

   D. All of the above Answer: Option D