需要三张表dept_emp,salaries,dept_manager
先根据题目在select后面写出需要的列名
根据列名,按顺序:
①先从表dept_emp中取数
②再连接表salaries
③最后通过表dept_manager限制列名emp_no

select d.dept_no,s.emp_no,s.salary FROM
dept_emp as d
left JOIN salaries as s
on s.emp_no = d.emp_no
where s.emp_no not in (select emp_no from dept_manager)