What is the number of students in each department?
select count(*), dept_code from student group by dept_code
Which one has the most students?
select * from student group by dept_code order by count(*) desc limit 1
What is that department's name and address?
select t2.dept_name, t2.dept_address from student as t1 join department as t2 on t1.dept_code = t2.dept_code group by t1.dept_code order by count(*) desc limit 1