subject ：

Find all employees last_name and first_name And corresponding dept_name_ Niuke Tiba _ Cattle from

There's an employee list employees A brief introduction is as follows :

There is a department table departments The table is summarized as follows :

There is one , Department employee relations form dept_emp A brief introduction is as follows :

Please find the of all employees last_name and first_name And corresponding dept_name, It also includes employees who have no assigned department for the time being , The output of the above example is as follows :

Answer key ：

Because employees without assigned department should also display , So take the employee table employees Subject to , You must output all the lines inside , Use it twice left join To connect three tables , The second time left join Is the last time left join The resulting temporary table is the same as the third table join.

select
    e.last_name,
    e.first_name,
    ds.dept_name
from
    employees e
left join
    dept_emp dp
on
    e.emp_no = dp.emp_no
left join
    departments ds
on
    dp.dept_no = ds.dept_no