获取所有非manager的员工emp_no

获取所有非manager的员工emp_no

CREATE TABLE `dept_manager` (
`dept_no` char(4) NOT NULL,
`emp_no` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
CREATE TABLE `employees` (
`emp_no` int(11) NOT NULL,
`birth_date` date NOT NULL,
`first_name` varchar(14) NOT NULL,
`last_name` varchar(16) NOT NULL,
`gender` char(1) NOT NULL,
`hire_date` date NOT NULL,
PRIMARY KEY (`emp_no`));

找到不包含在dept_manager里的employees
1.在employees里 不在dept_manager

select emp_no
from employees
where emp_no not in 
(select emp_no
 from dept_manager)

2.在employees里，dept_no为空

select e.emp_no
from employees as e
left join dept_manager as d
/*要用left join 不能用inner join*/
on e.emp_no=d.emp_no
where d.dept_no is null
/*用and会输出全部employees*/