存在同个用户多次进入直播的情况 | #牛客直播各科目出勤率#
牛客直播各科目出勤率
https://www.nowcoder.com/practice/0cab547df4f0430b93042128f445d899
SELECT
course_id,
course_name,
ROUND(100 * COUNT(DISTINCT CASE WHEN timestampdiff(second, in_datetime, out_datetime) >= 10*60 THEN a.user_id END) / COUNT(DISTINCT CASE WHEN if_sign = 1 THEN b.user_id END), 2) AS attend_rate
FROM
course_tb
JOIN
behavior_tb b USING(course_id)
JOIN
attend_tb a USING(course_id)
GROUP BY
course_id, course_name
ORDER BY
course_id
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