题解 | 请写出计算粉丝ctr的sql语句

该题表达不清晰，没有做好解释，题目实际考的是“某条内容只被该内容创作者的粉丝所产生的行为”，而c表的用户行为表中会有不是该内容创作者粉丝的曝光阅读行为，限制作者与粉丝关系的join逻辑可以使用in的方式写

select

sum(read_num)/sum(show_num) as fans_ctr

from

(

select

c.content_id

,c.fans_id

,b.author_id

,sum(show_num) as show_num

,sum(read_num) as read_num

from c

inner join b

on c.content_id=b.content_id

group by c.content_id

,c.fans_id

,b.author_id

) t1

inner join a

on t1.author_id=a.author_id and t1.fans_id=a.fans_id