For the following database schema, write SQL queries to retrieve the specified data. • PersonID FirstName LastName DateOfBirth• Student UserName StudentID Major StartDate AcademicLevel • Instructor UserName Instructorld Position StartDate Department • Course CourselD Title Description Credits Department• Section SectionID Coursel Semester Year Capacity InstructorID • Enroll StudentID SectionID GradeThe total number of students enrolled in all sections of the course titled "Database Systems"The number of distinct instructors that taught courses is the fall semester of year 2018The instructors that taught the "operating systems" course but not the "database systems" courseThe first and last names of students that got an A grade in the "Networking" course but not an A grade in the "Advanced Networking" courseThe total number of credits for each studentSubmissionSubmit all answers in a single file.