Mysql的，AVG和COUNT問題

Question

ID, rating_id , rating_num 

33100, '4028',  2, 
33099, '4041',  2, 
33098, '1889',  4, 
33097, '1889',  5, 
33096, '4050',  2, 
33095, '8578',  2, 
33094, '8578',  4, 
33093, '8578',  5, 
33093, '8578',  5, 

傢伙3個問題

1）我如何才能看到它rating_id已收到rating_num超過三項罪名？ （答案：8578）

2）如何查看每個rating_id的平均rating_num？

3）我怎樣才能看到每個rating_id的平均rating_num收到超過三個計數的rating_num？ （回答：4）

感謝回答的Mysql4dumbmies

Answer 1

select rating_id 
    from YourTable 
    group by rating_id 
    having count(*) > 3 

select rating_id, avg(rating_num) as average_rating 
    from YourTable 
    group by rating_id 

select rating_id, avg(rating_num) as average_rating 
    from YourTable 
    group by rating_id 
    having count(*) > 3 

的類裏面attender