+---------------+---------+
| Column Name | Type |
+---------------+---------+
| ad\_id | int |
| user\_id | int |
| action | enum |
+---------------+---------+
(ad\_id, user\_id) is the primary key for this table.
Each row of this table contains the ID of an Ad, the ID of a user and the action taken by this user regarding this Ad.
The action column is an ENUM type of ('Clicked', 'Viewed', 'Ignored').
A company is running Ads and wants to calculate the performance of each Ad.
Performance of the Ad is measured using Click-Through Rate (CTR) where:
Write an SQL query to find the ctr of each Ad.
Roundctr to 2 decimal points. Order the result table by ctr in descending order and by ad_id in ascending order in case of a tie.
The query result format is in the following example:
Ads table:
+-------+---------+---------+
| ad\_id | user\_id | action |
+-------+---------+---------+
| 1 | 1 | Clicked |
| 2 | 2 | Clicked |
| 3 | 3 | Viewed |
| 5 | 5 | Ignored |
| 1 | 7 | Ignored |
| 2 | 7 | Viewed |
| 3 | 5 | Clicked |
| 1 | 4 | Viewed |
| 2 | 11 | Viewed |
| 1 | 2 | Clicked |
+-------+---------+---------+
Result table:
+-------+-------+
| ad\_id | ctr |
+-------+-------+
| 1 | 66.67 |
| 3 | 50.00 |
| 2 | 33.33 |
| 5 | 0.00 |
+-------+-------+
for ad\_id = 1, ctr = (2/(2+1)) * 100 = 66.67
for ad\_id = 2, ctr = (1/(1+2)) * 100 = 33.33
for ad\_id = 3, ctr = (1/(1+1)) * 100 = 50.00
for ad\_id = 5, ctr = 0.00, Note that ad\_id = 5 has no clicks or views.
Note that we don't care about Ignored Ads.
Result table is ordered by the ctr. in case of a tie we order them by ad\_id
