官方题解 | #小破站9月新会员人数#
小破站9月新会员人数
http://www.nowcoder.com/practice/aaa8bf0381cf4f6ca53665cea37e405e
大会员生效开始日期在’2021-9-1‘和‘2021-9-31’日之间并且没在‘2021-9-1’之前出现过的不重复用户的个数即为9月份新会员的人数。
SELECT count(distinct user_id) as new_cnt
FROM detail_list_tb
WHERE begin_date BETWEEN '2021-9-1' AND '2021-9-30'
AND user_id NOT IN
(
SELECT user_id from detail_list_tb
WHERE begin_date<'2021-9-1'
);
