text: # https://leetcode.com/problems/get-highest-answer-rate-question/
  
  select t1.question_id as survey_log from
  (select question_id from survey_log where answer_id IS NOT NULL) as t1
  GROUP BY t1.question_id
  ORDER BY count(t1.question_id) DESC
  LIMIT 1;
  
  # Another solution
  SELECT
      question_id survey_log
  FROM survey_log
  GROUP BY 1
  ORDER BY SUM(IF(answer_id is not null, 1, 0))/COUNT(IF(action='show',1,0)) desc
  LIMIT 1