题解 | #浙大不同难度题目的正确率#

-- 条件：浙江大学，不同难度，正确率,升序
SELECT
difficult_level,
round(SUM(IF(result='right',1,0)) / count(question_id),4) AS correct_rate
FROM user_profile
INNER JOIN question_practice_detail USING(device_id)
INNER JOIN question_detail USING(question_id)
WHERE university='浙江大学'
GROUP BY difficult_level
ORDER BY correct_rate;