13e.     Get a list of students (by name) who have had Professor Johnson (‘Johnson, J.C.’). If a student took more than one class with Professor Johnson, list them only once.

 

            SELECT DISTINCT studentname

            FROM professor, class, student

            WHERE profname = ‘Johnson, J.C.’

            AND professor.profID = class.profID

            AND class.studentID = student.studentID;