What is the city code of the city that the most students live in?
select city_code from student group by city_code order by count ( * ) desc limit 1
What is the city code of the city that the least students live in?
select city_code from student group by city_code order by count ( * ) limit 1
What is the average age of all the students?
select avg ( age ) from student
What are the majors of all the students with sex F?
select major from student where sex = "F"