题解 | 错了很多次

select
    e.emp_no emp_no,
    salary,
    last_name,
    first_name
from
    employees e
    join salaries s on e.emp_no = s.emp_no
where
    salary = (
        select
            max(salary)
        from
            salaries
        where
            salary < (
                select
                    max(salary)
                from
                    salaries
                where
                    to_date = '9999-01-01'
            )
            and to_date = '9999-01-01'
    )
    and to_date = '9999-01-01'

SQL运算逻辑从里到外，表头字段名唯一可不用加表名前缀