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'
