题解 | 平均工资

select
    avg(salary)
from
    salaries
where
    to_date = '9999-01-01'
    and (
        salary <> (
            select
                max(salary)
            from
                salaries
            where to_date = '9999-01-01'
        )
        and salary <> (
            select
                min(salary)
            from
                salaries
            where to_date = '9999-01-01'
        )
    )