题解 | #平均工资#

两次子查询，分别去除最大值与最小值
select
    avg(salary) avg_salary
from
    salaries
where
    salary not in (
        select
            max(salary)
        from
            salaries
        where
            to_date = '9999-01-01'
    )
    and salary not in (
        select
            min(salary)
        from
            salaries
        where
            to_date = '9999-01-01'
    )
    AND to_date = '9999-01-01'