[MySQL] From절의 서브쿼리 요약

Table = "lol_feedbacks"

 

1)

SELECT * FROM lol_feedbacks ORDER BY satisfaction_score DESC, feedback_date DESC;

2)

SELECT user_name, max(feedback_date) FROM lol_feedbacks GROUP BY user_name;

3)

SELECT count(*) FROM lol_feedbacks WHERE satisfaction_score = 5;

4)

SELECT user_name, COUNT(feedback_date) AS feedback_count FROM lol_feedbacks GROUP BY user_name ORDER BY feedback_count DESC LIMIT 3;

5)

SELECT feedback_date FROM (SELECT feedback_date, AVG(satisfaction_score) AS avg_satisfaction FROM lol_feedbacks GROUP BY feedback_date) subquery ORDER BY avg_satisfaction DESC LIMIT 1;

 

 

5) 평균 만족도 점수가 가장 높은 날짜를 찾아라 (수정 답안)

SELECT feedback_date FROM lol_feedbacks GROUP BY feedback_date ORDER BY avg(satisfaction_score) DESC LIMIT 1;