For each department, what is the corresponding number of professors?
select count(*), t1.dept_code from professor as t1 join department as t2 on t1.dept_code = t2.dept_code group by t1.dept_code
For the department with the fewest professors, what is its name and code?
select t2.dept_name, t1.dept_code from professor as t1 join department as t2 on t1.dept_code = t2.dept_code group by t1.dept_code order by count(*) limit 1