题目链接：​​点击打开链接​​

题目大意：略。

解题思路：略。

AC 代码

SELECT query_name, ROUND(AVG(rating / position), 2) quality, ROUND(COUNT(IF(rating < 3, 1, null)) / COUNT(*) * 100, 2) poor_query_percentage
FROM Queries
GROUP BY query_name