# Get Highest Answer Rate Question Problem

## Description

LeetCode Problem 578.

Get the highest answer rate question from a table survey_log with these columns: id, action, question_id, answer_id, q_num, timestamp.

id means user id; action has these kind of values: “show”, “answer”, “skip”; answer_id is not null when action column is “answer”, while is null for “show” and “skip”; q_num is the numeral order of the question in current session.

Write a sql query to identify the question which has the highest answer rate.

Example:

``````1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Input:
+------+-----------+--------------+------------+-----------+------------+
| id   | action    | question_id  | answer_id  | q_num     | timestamp  |
+------+-----------+--------------+------------+-----------+------------+
| 5    | show      | 285          | null       | 1         | 123        |
| 5    | answer    | 285          | 124124     | 1         | 124        |
| 5    | show      | 369          | null       | 2         | 125        |
| 5    | skip      | 369          | null       | 2         | 126        |
+------+-----------+--------------+------------+-----------+------------+
Output:
+-------------+
| survey_log  |
+-------------+
|    285      |
+-------------+
Explanation:
question 285 has answer rate 1/1, while question 369 has 0/1 answer rate, so output 285.
``````

Note: The highest answer rate meaning is: answer number’s ratio in show number in the same question.

## MySQL Solution

``````1
2
3
4
5
select question_id as 'survey_log'
from survey_log
group by question_id
order by count(answer_id) / sum(if(action = 'show', 1, 0)) desc
limit 1
``````