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Consider the set of relations shown below and the SQL query that follows:
Students: (Roll_number, Name, Data_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 Grades.grade
and courses. Instructor = korth
and Courses.course - number = Grades.course - number
Roll_number = Grades.Roll_number and Grades.grade = A
Which of the following sets is computed by the above query?
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- Names of students who have got an A grade in all courses taught by Korth
- Names of students who have got an A grade in all courses
- Names of students who have got an A grade in at least one of the courses taught by Korth
- None of the above
- Names of students who have got an A grade in all courses taught by Korth
Correct Option: C
The relations are as given,
Students: (Roll_number, Name, Date_of_birth)
Courses: (Course number, Course_name, Instructor)
Grades: (Roll_number, Course_number, Grade)
Now, the distinct name is to be selected, where
1. Name of the student is selected on the basis of the grade.
2. Instructor of the course in Korth.
3. Courses selected on the basis of grade.
4. Grade should be A.
The query thus, computed is name of the students who gets A grade in atleast one of the courses taught by Korth .
