18.查找当前薪水(to_date='9999-01-01')排名第二多的员工编号

查找当前薪水(to_date='9999-01-01')排名第二多的员工编号emp_no、薪水salary、last_name以及first_name，不准使用order by

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`));

CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));

解析：SB题目，为什么不让用order by

select e.emp_no, max(s.salary), e.last_name, e.first_name
from employees as e, salaries as s
where s.to_date = '9999-01-01'
and e.emp_no = s.emp_no
and s.salary not in (
    select max(salary)
    from salaries
    where to_date = '9999-01-01'
)