Table: Signups
+----------------+----------+ +| Column Name | Type | ++----------------+----------+ +| user_id | int | +| time_stamp | datetime | ++----------------+----------+ +user_id is the column of unique values for this table. +Each row contains information about the signup time for the user with ID user_id. ++ +
+ +
Table: Confirmations
+----------------+----------+
+| Column Name | Type |
++----------------+----------+
+| user_id | int |
+| time_stamp | datetime |
+| action | ENUM |
++----------------+----------+
+(user_id, time_stamp) is the primary key (combination of columns with unique values) for this table.
+user_id is a foreign key (reference column) to the Signups table.
+action is an ENUM (category) of the type ('confirmed', 'timeout')
+Each row of this table indicates that the user with ID user_id requested a confirmation message at time_stamp and that confirmation message was either confirmed ('confirmed') or expired without confirming ('timeout').
+
+
++ +
The confirmation rate of a user is the number of 'confirmed' messages divided by the total number of requested confirmation messages. The confirmation rate of a user that did not request any confirmation messages is 0. Round the confirmation rate to two decimal places.
Write a solution to find the confirmation rate of each user.
+ +Return the result table in any order.
+ +The result format is in the following example.
+ ++
Example 1:
+ +Input: +Signups table: ++---------+---------------------+ +| user_id | time_stamp | ++---------+---------------------+ +| 3 | 2020-03-21 10:16:13 | +| 7 | 2020-01-04 13:57:59 | +| 2 | 2020-07-29 23:09:44 | +| 6 | 2020-12-09 10:39:37 | ++---------+---------------------+ +Confirmations table: ++---------+---------------------+-----------+ +| user_id | time_stamp | action | ++---------+---------------------+-----------+ +| 3 | 2021-01-06 03:30:46 | timeout | +| 3 | 2021-07-14 14:00:00 | timeout | +| 7 | 2021-06-12 11:57:29 | confirmed | +| 7 | 2021-06-13 12:58:28 | confirmed | +| 7 | 2021-06-14 13:59:27 | confirmed | +| 2 | 2021-01-22 00:00:00 | confirmed | +| 2 | 2021-02-28 23:59:59 | timeout | ++---------+---------------------+-----------+ +Output: ++---------+-------------------+ +| user_id | confirmation_rate | ++---------+-------------------+ +| 6 | 0.00 | +| 3 | 0.00 | +| 7 | 1.00 | +| 2 | 0.50 | ++---------+-------------------+ +Explanation: +User 6 did not request any confirmation messages. The confirmation rate is 0. +User 3 made 2 requests and both timed out. The confirmation rate is 0. +User 7 made 3 requests and all were confirmed. The confirmation rate is 1. +User 2 made 2 requests where one was confirmed and the other timed out. The confirmation rate is 1 / 2 = 0.5. ++