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,

伙计3个问题

1）我怎样才能看到哪个rating_id收到了三个以上的rating_num？（答案：8578）

2）我怎样才能看到每个rating_id的平均rating_num？

3）我怎样才能看到每个rating_id的平均rating_num收到三个以上的rating_num？（答案：4）

感谢您回复Mysql4dumbmies的课程参与者

Answer 1

1

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

2

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

3

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

Mysql，AVG和Count问题

1 个答案: