题解 | #分组过滤练习题#
平均活跃天数和月活人数
http://www.nowcoder.com/practice/9e2fb674b58b4f60ac765b7a37dde1b9
SELECT COUNT(DISTINCT device_id) as did_cnt,count(question_id) as question_cnt
FROM question_practice_detail
WHERE date BETWEEN '2021-08-01' AND '2021-09-01';