UGC NET CSE | December 2007 | Part 2 | Question: 20

Question

Consider the query :

SELECT student_name FROM students WHERE 
class_name=(SELECT class_name FROM students WHERE math_marks=100); 

what will be the output ?

• A. the list of names of students with $100$ marks in mathematics

• B. the names of all students of all classes in which at least one student has $100$ marks in mathematics

• C. the names of all students in all classes having $100$ marks in mathematics

• D. the names and class of all students whose marks in mathematics is $100$

Answer 1

A)the list of names of students with 100 marks in mathematics

Comments

Wrong answer. Answer should be B. It gives names of all students of classes where atleast one student scored 100 in mathematics.

Answer 2

answer is B
“class_name=(SELECT class_name FROM students WHERE math_marks=100)”

Selecting classname of students who have scored 100 marks in maths , 
from a relation called student .

 “SELECT student_name FROM students WHERE class_name= “

Selecting student names from the student relation where there’s atleast 
1 student who has scored 100 marks in math..
So basically printing names of all students of a classname in which 
atleast 1 student has scored 100 marks in math .