get-highest-answer-rate-question

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578. Get Highest Answer Rate Question (Medium)

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

uid 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:

Input:
+------+-----------+--------------+------------+-----------+------------+
| uid  | 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.

Related Topics

[Database]

Hints

Hint 1

Try to find all question ids by group

Hint 2

Try to find each group answer number and show number.

Hint 3

Rank all the rates (answer/(answer+show)) and return the max one