题解 | #使用含有关键字exists查找未分配具体部门的员工的所有信息。#

select * from employees where not exists 
(select emp_no from dept_emp where employees.emp_no = dept_emp.emp_no);

select * from employees where emp_no not in
(select emp_no from dept_emp where employees.emp_no = dept_emp.emp_no);

select * from employees e where emp_no not in
(select emp_no from dept_emp);

select a.emp_no,a.birth_date,a.first_name,a.last_name,
a.gender,a.hire_date
from(select e.*,d.dept_no from employees  e left join dept_emp d on e.emp_no=d.emp_no)a
where a.dept_no is null;