select de.dept_no,d.dept_name,t.title,count(t.title) as count FROM departments as d JOIN dept_emp as de ON d.dept_no = de.dept_no JOIN titles as t ON de.emp_no = t.emp_no WHERE de.to_date = '9999-01-01' and t.to_date = '9999-01-01' GROUP BY de.dept_no,t.title ORDER BY de.dept_no,t.title 重点在于group ...