NIELIT STA 2021

Question

Consider the relations:

$R_{1}${Roll_No, Name, Grades} and 

$R_{2}${Roll_No, Subject_ID, Grades}

Which of the following operations cannot be performed using the above relations? 

 

• A. Union 
• B. Select 
• C. Join
• D. Project

Answer 1

Answer: A

R1 and R2 is not union compatible.

SQL UNION Operator (w3schools.com)

Set operations (SQL) - Wikipedia