select a.dept_no,d.dept_name,a.title,a.count
from departments d
left join
(select de.dept_no,t.title,count(t.emp_no) as count
from dept_emp de
left join titles t
on de.emp_no=t.emp_no
group by de.dept_no,t.title) a
on d.dept_no=a.dept_no
order by d.dept_no,a.title;

不按title排序题目也算我错，不知道为啥就给加上去了