题解 | 请写出计算粉丝ctr的sql语句
select round(sum(read_num) / sum(show_num), 4) fans_ctr from c where (content_id, fans_id ) in ( select content_id ,fans_id from a join b on a.author_id = b.author_id )
select round(sum(read_num) / sum(show_num), 4) fans_ctr from c where (content_id, fans_id ) in ( select content_id ,fans_id from a join b on a.author_id = b.author_id )
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