题解 | #21年8月份练题总数#
21年8月份练题总数
http://www.nowcoder.com/practice/b8f30b239b454ed490367b53ea95607d
掌握count(distinct column_name)的用法
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 '2021-08-31'