题解 |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
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
WITH t1 AS ( SELECT * FROM answer_tb LEFT JOIN issue_tb USING(issue_id)) SELECT COUNT(DISTINCT a.author_id) AS num FROM t1 AS a JOIN t1 AS b ON a.author_id = b.author_id WHERE a.issue_type = 'Career' AND b.issue_type = 'Education'