SELECT v.video_id, ROUND(SUM(CASE WHEN TIMESTAMPDIFF(SECOND, uv.start_time, uv.end_time) >= v.duration THEN 1 ELSE 0 END) / COUNT(*), 3) AS completion_rate FROM tb_user_video_log uv JOIN tb_video_info v ON uv.video_id = v.video_id WHERE YEAR(uv.start_time) = 2021 GROUP BY v.video_id ORDER ...