难乎-题解 | 教育类问题的用户里有多少回答过职场类问题#

# 请你统计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，以上例子的输出结果如下：


select count(distinct author_id) as num 
from answer_tb
where issue_id like 'C%' 
    and 
    author_id in
    (select author_id 
        from answer_tb where issue_id like 'E%'
    );





select count(distinct author_id) num 
from issue_tb t1 
join answer_tb t2 
on t1.issue_id=t2.issue_id 
where issue_type = 'Education'
and author_id in (
                 select author_id
                 from issue_tb a 
                 join answer_tb b 
                 on a.issue_id=b.issue_id 
                 where issue_type = 'Career'
                 )