Leetcode_数据库刷题_578. 查询回答率最高的问题

578题. 查询回答率最高的问题
SQL架构：

Create table If Not Exists survey_log (id int, action varchar(255), question_id int, answer_id int, q_num int, timestamp int)
Truncate table survey_log
insert into survey_log (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'show', '285', 'None', '1', '123')
insert into survey_log (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'answer', '285', '124124', '1', '124')
insert into survey_log (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'show', '369', 'None', '2', '125')
insert into survey_log (id, action, question_id, answer_id, q_num, timestamp) values ('5', 'skip', '369', 'None', '2', '126')

从 survey_log 表中获得回答率最高的问题，survey_log 表包含这些列：id, action, question_id, answer_id, q_num, timestamp。
id 表示用户 id；action 有以下几种值：“show”，“answer”，“skip”；当 action 值为 “answer” 时 answer_id 非空，而 action 值为 “show” 或者 “skip” 时 answer_id 为空；q_num 表示当前会话中问题的编号。
问题：请编写 SQL 查询来找到具有最高回答率的问题。
示例：
输入：

输出：

解释：问题 285 的回答率为 1/1，而问题 369 回答率为 0/1，因此输出 285 。
解答：

select  question_id  as survey_log  from survey_log 
group by question_id
order by sum(if(action='answer',1,0))/count(*) desc
limit 1;
或
select question_id as survey_log from survey_log
group by question_id
order by 
   sum(case when action='answer' then 1 else 0 end)/sum(case when action='show' then 1 else 0 end) desc
limit 1;
或
select question_id as survey_log from survey_log
group by question_id
order by 
    sum(if(action = 'answer',1,0))/sum(if(action = 'show',1,0)) desc
limit 1;

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/get-highest-answer-rate-question