题解 | #试卷发布当天作答人数和平均分#

SELECT
    ei.exam_id,
    count(DISTINCT uid) uv,
    round(avg(score), 1) avg_score
FROM
    examination_info ei
JOIN exam_record er USING (exam_id)
JOIN user_info ui USING (uid)
WHERE
    submit_time IS NOT NULL
AND score IS NOT NULL
AND ui. LEVEL > 5
AND tag = "SQL"
AND TO_DAYS(start_time) = TO_DAYS(release_time)
GROUP BY
    exam_id
ORDER BY
    uv DESC,
    avg_score ASC