题解 | #查找所有员工的last_name和first_name以及对应的dept_name#
select e.last_name,e.first_name,nde.dept_name from employees as e left join (select de.dept_no,de.emp_no,d.dept_name from dept_emp as de left join departments as d on de.dept_no = d.dept_no) as nde on e.emp_no = nde.emp_no
思路:
三表联合查询，先连接部门表，然后连接员工表
