select e2.last_name, e2.first_name, deps.dept_name from ( select e.emp_no, de.dept_no, e.first_name, e.last_name from employees e left join dept_emp de on e.emp_no = de.emp_no ) as e2 left join departments deps on e2.dept_no = deps.dept_no 先通过第一次left join将employees和dept_emp连接起来，查询出所有的emplo...
