select e.emp_no,s.salary,e.last_name,e.first_name
from employees e,salaries s,(
    select max(salary) salary
    from salaries
    where salary != (
        select max(salary) salary
        from salaries
    ) # firstMax
) secondMax
where e.emp_no = s.emp_no and s.salary = secondMax.salary

把最大工资排除后,剩下数据的最大工资就是第二工资