Show all the staff.
select * from staff
What is the assignment period for each staff?
select date_assigned_to - date_assigned_from from staff_department_assignments
Find the id and name of the staff who has been assigned for the shortest period.
select t1.staff_id, t1.staff_name from staff as t1 join staff_department_assignments as t2 on t1.staff_id = t2.staff_id order by date_assigned_to - date_assigned_from limit 1