GATE | GATE-CS-2003 | Question 86

Consider the set of relations shown below and the SQL query that follows.

Students: (Roll_number, Name, Date_of_birth)
  Courses: (Course number, Course_name, Instructor)
  Grades: (Roll_number, Course_number, Grade)

 select distinct Name
         from Students, Courses, Grades
         where Students. Roll_number = Grades.Roll_number
              and Courses.Instructor = Korth
              and Courses.Course_number = Grades.Course_number
              and Grades.grade = A

Which of the following sets is computed by the above query?
(A) Names of students who have got an A grade in all courses taught by Korth
(B) Names of students who have got an A grade in all courses
(C) Names of students who have got an A grade in at least one of the courses taught by Korth
(D) None of the above


Answer: (C)

Explanation: The query gives the name of all the students who have scored “A” grade in any of the courses that are taught by Korth.
So, C is the correct choice.


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