Which department has more than 1 head at a time? List the ID, Name  and the number of heads.
select t1.department_id, t1.name, count ( * ) from management as t2 join department as t1 on t1.department_id = t2.department_id group by t1.department_id having count ( * ) > 1
Which Department has the most number of employee? tell me the rank and creation year.
select ranking, creation from department where num_employees = ( select max ( num_employees ) from department )
Which Department has the least number of employee? tell me the rank and creation year.
select ranking, creation from department where num_employees = ( select min ( num_employees ) from department )
Which Department has the highest Budget value? tell me the rank and creation year.
select ranking, creation from department where budget_in_billions = ( select max ( budget_in_billions ) from department )