1. Consider the following relations:
   Student (student_no, name, address, GPA)
   
   Course (course_no, title, texbook)
   
   Instructor (instructor_no, name, phone_no, specialization)
   
   Registration (student_no, course_no, instructor_no, session)
   
   Qualified_to_teach (instructor_no, course_no)
   
   Determine the relationships among these relations. List the primary keys for each relation and any foreign keys necessary to establish the relationships and maintain referential integrity.
   Write SQL query to list the names of instructors who have taught COMP 378 but not COMP 418 during the following sessions: Winter 2020 and Winter 2021