[SQL] Matching Grades and Ordering (등급 부여하고 정렬하기)

Ketty gives Eve a task to generate a report containing three columns: Name, Grade and Mark. Ketty doesn't want the NAMES of those students who received a grade lower than 8. The report must be in descending order by grade -- i.e. higher grades are entered first. If there is more than one student with the same grade (8-10) assigned to them, order those particular students by their name alphabetically. Finally, if the grade is lower than 8, use "NULL" as their name and list them by their grades in descending order. If there is more than one student with the same grade (1-7) assigned to them, order those particular students by their marks in ascending order. (https://www.hackerrank.com/challenges/the-report/problem?isFullScreen=true)

select 
    case
        when G.grade IN (1,2,3,4,5,6,7) then Null
        else S.Name
        end as N
    , s.Marks, g.Grade
from 
    Students s
    join Grades g
    on s.Marks between g.Min_Mark and g.Max_Mark
order by 
    g.Grade desc,
    case
        when g.Grade >= 8 then Name
        else Marks 
        end