题解 | #某乎问答回答过教育类问题的用户里有多少用户回#
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
select count(d.author_id) num
from (
select author_id,count(issue_type) cnt
from
(
select issue_type,author_id from answer_tb a,issue_tb b
where a.issue_id=b.issue_id
group by issue_type,author_id
) c
where c.issue_type in ('Education','Career')
group by author_id
having cnt>=2
) d