SELECT
    CASE
        WHEN g.min_mark >=70 THEN s.name
        ELSE NULL
    END AS name,
    grade,
    marks
FROM
    students s
    JOIN grades g ON s.marks BETWEEN g.min_mark AND g.max_mark
ORDER BY
    grade DESC, name,
    (CASE
        WHEN name IS NULL THEN grade
    END) DESC,
    marks;