题解 | #教育类问题的用户里多少用户回答过职场类问题#
某乎问答回答过教育类问题的用户里有多少用户回答过职场类问题
https://www.nowcoder.com/practice/b02cf9ee7b9f4cdda308f8155ff3415d
#不同问题类型回答次数,筛选出大于0次的
select sum(c) a ,sum(e) b,author_id
from (SELECT *
,if(b.issue_type='Career',1,0) as c
,if(b.issue_type='Education',1,0) as e
from answer_tb a join issue_tb b USING(issue_id)
)a
GROUP BY author_id
HAVING a>0 and b>0
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