# 1934. Confirmation Rate

<https://leetcode.com/problems/confirmation-rate>

## Description

Table: `Signups`

```
+----------------+----------+
| Column Name    | Type     |
+----------------+----------+
| user\_id        | int      |
| time\_stamp     | datetime |
+----------------+----------+
user\_id is the primary key 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 for this table.
user\_id is a foreign key with a reference to the Signups table.
action is an ENUM 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 an SQL query to find the **confirmation rate** of each user.

Return the result table **in any order**.

The query result format is in the following example:

```
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   |
+---------+---------------------+-----------+
Result table
+---------+-------------------+
| user\_id | confirmation\_rate |
+---------+-------------------+
| 6       | 0.00              |
| 3       | 0.00              |
| 7       | 1.00              |
| 2       | 0.50              |
+---------+-------------------+
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.
```

## ac

```java
```
