問題描述

問題解答

select count(author_id) as num from (select author_id,created from posts GROUP BY author_id HAVING count(id)=1) as t where t.created BETWEEN ’2016-09-020 00:00:00’ and ’2016-09-20 23:59:59’;

嗯，這個問題....

難道不是按照時間排序就可以了嗎？

select min(issue_date) md ,user_id from table group by user_id where md = ’9.20’