如何实现Oracle先组内排序然后再组外排序

select

    T1.*

from

    (

    select

        ID,

        DEPARTMENT,

        CREATE_TM,

        level,

        row_number() over (partition by DEPARTMENT

    order by

        level desc) as NUM

    from

        USER_INFO

    where

        DEPARTMENT is not null) T1

left join (

    select

        ROWNUM SEQ,

        DEPARTMENT

    from

        (

        select

            DEPARTMENT,

            MAX(CREATE_TM)

        from

            USER_INFO

        group by

            DEPARTMENT

        order by

            MAX(CREATE_TM))) T2 on

    T1.DEPARTMENT = T2.DEPARTMENT

order by

    T2.SEQ desc,

    T1.LEVEL asc;