SELECT
    de.dept_no,
    e.emp_no,
    salary
FROM employees e # join 就完事儿了
JOIN dept_emp de
ON e.emp_no = de.emp_no
JOIN dept_manager dm
ON de.dept_no = dm.dept_no
JOIN salaries s
ON e.emp_no = s.emp_no
WHERE s.to_date = '9999-01-01' AND e.emp_no NOT IN (SELECT
                                                        emp_no
                                                    FROM dept_manager) #非领导条件
ORDER BY de.dept_no, salary DESC # 隐藏条件