-- 三链表 SELECT d.dept_no, d.dept_name, COUNT(*) AS sum FROM departments AS d, dept_emp AS de, salaries AS s WHERE d.dept_no=de.dept_no AND de.emp_no=s.emp_no GROUP BY d.dept_no;-- 我的方法 -- 有隐患,dept_no 和dept_name 要一一对应 SELECT d1.dept_no,d1.dept_name,count(*) as sum FROM ( SELECT de.emp_no,d.dept_...