Question

Consider the following relational schema: Students (rollno: integer, name: string, age: integer, cgpa: real) Courses (courseno: integer, cname: string, credits: integer) Enrolled (rollno: integer, courseno: integer, grade: string) Which of the following options is/are correct SQL query/queries to retrieve the names of the students enrolled in course number (i.e., courseno) 1470?

Accepted Answer

(A) SELECT S.name
FROM Students S
WHERE EXISTS (SELECT * FROM Enrolled E
              WHERE E.courseno = 1470
              AND E.rollno = S.rollno);; (C) SELECT S.name
FROM Students S
WHERE 0 < (SELECT COUNT(*)
           FROM Enrolled E
           WHERE E.courseno = 1470
           AND E.rollno = S.rollno);; (D) SELECT S.name
FROM Students S NATURAL JOIN Enrolled E
WHERE E.courseno = 1470;

Answer

SELECT S.name
FROM Students S
WHERE EXISTS (SELECT * FROM Enrolled E
              WHERE E.courseno = 1470
              AND E.rollno = S.rollno);

Answer

SELECT S.name
FROM Students S
WHERE SIZEOF (SELECT * FROM Enrolled E
              WHERE E.courseno = 1470
              AND E.rollno = S.rollno) > 0;

Answer

SELECT S.name
FROM Students S
WHERE 0 < (SELECT COUNT(*)
           FROM Enrolled E
           WHERE E.courseno = 1470
           AND E.rollno = S.rollno);

Answer

SELECT S.name
FROM Students S NATURAL JOIN Enrolled E
WHERE E.courseno = 1470;

GATE 2025 CS (CS2) – Question 54

Explanation