occupation 질문!

안녕하세요 선생님! 강의 잘 듣고 있습니다.

해당 문제 이렇게도 풀이했는데 답은 정상적으로 나오나 hackerranks에서는 오답으로 나와서 질문드립니다!

이렇게 풀어도 되는지, 어떤 부분에 주의해야할지 여쭤볼 수 있을까요?

SELECT 
    SUM(CASE WHEN sub.occupation='Doctor' THEN sub.name ELSE NULL END) doctor,
    SUM(CASE WHEN sub.occupation='Professor' THEN sub.name ELSE NULL END) professor,
    SUM(CASE WHEN sub.occupation='Singer' THEN sub.name ELSE NULL END) singer,
    SUM(CASE WHEN sub.occupation='Actor' THEN sub.name ELSE NULL END) actor
FROM (
    SELECT name, occupation, ROW_NUMBER() OVER(PARTITION BY occupation ORDER BY NAME) AS number
    FROM occupations) AS sub
GROUP BY sub.number
ORDER BY sub.number;

SELECT (SELECT name FROM occupation WHERE occupation = 'Doctor'), 
    (SELECT name FROM occupation WHERE occupation = 'Professor'),
    (SELECT name FROM occupation WHERE occupation = 'Singer'),
    (SELECT name FROM occupation WHERE occupation = 'Actor')
FROM occupation
ORDER BY name

SELECT MIN('Doctor')
     , MAX('Doctor')
     , SUM('Doctor')
FROM occupations