题解 | 查找所有员工的last_name和first_name以及对应的dept_name

with total_departments as (
    select 
        d_e.emp_no,
        d_e.dept_no,
        d.dept_name
    from 
        dept_emp as d_e
    left join 
        departments as d
    on 
        d_e.dept_no = d.dept_no
) 

select 
    e.last_name,
    e.first_name,
    t_d.dept_name
from 
    employees as e
left join 
    total_departments as t_d
on 
    e.emp_no = t_d.emp_no