# 2720. Popularity Percentage

## Description

Table: Friends

+-------------+------+
| Column Name | Type |
+-------------+------+
| user1       | int  |
| user2       | int  |
+-------------+------+
(user1, user2) is the primary key of this table.
Each row contains information about friendship where user1 and user2 are friends.

Write an SQL query to find the popularity percentage for each user on Meta/Facebook. The popularity percentage is defined as the total number of friends the user has divided by the total number of users on the platform, then converted into a percentage by multiplying by 100, rounded to 2 decimal places.

Return the result table ordered by user1 in ascending order.

The query result format is in the following example.

Example 1:

Input:
Friends table:
+-------+-------+
| user1 | user2 |
+-------+-------+
| 2     | 1     |
| 1     | 3     |
| 4     | 1     |
| 1     | 5     |
| 1     | 6     |
| 2     | 6     |
| 7     | 2     |
| 8     | 3     |
| 3     | 9     |
+-------+-------+
Output:
+-------+-----------------------+
| user1 | percentage_popularity |
+-------+-----------------------+
| 1     | 55.56                 |
| 2     | 33.33                 |
| 3     | 33.33                 |
| 4     | 11.11                 |
| 5     | 11.11                 |
| 6     | 22.22                 |
| 7     | 11.11                 |
| 8     | 11.11                 |
| 9     | 11.11                 |
+-------+-----------------------+
Explanation:
There are total 9 users on the platform.
- User "1" has friendships with 2, 3, 4, 5 and 6. Therefore, the percentage popularity for user 1 would be calculated as (5/9) * 100 = 55.56.
- User "2" has friendships with 1, 6 and 7. Therefore, the percentage popularity for user 2 would be calculated as (3/9) * 100 = 33.33.
- User "3" has friendships with 1, 8 and 9. Therefore, the percentage popularity for user 3 would be calculated as (3/9) * 100 = 33.33.
- User "4" has friendships with 1. Therefore, the percentage popularity for user 4 would be calculated as (1/9) * 100 = 11.11.
- User "5" has friendships with 1. Therefore, the percentage popularity for user 5 would be calculated as (1/9) * 100 = 11.11.
- User "6" has friendships with 1 and 2. Therefore, the percentage popularity for user 6 would be calculated as (2/9) * 100 = 22.22.
- User "7" has friendships with 2. Therefore, the percentage popularity for user 7 would be calculated as (1/9) * 100 = 11.11.
- User "8" has friendships with 3. Therefore, the percentage popularity for user 8 would be calculated as (1/9) * 100 = 11.11.
- User "9" has friendships with 3. Therefore, the percentage popularity for user 9 would be calculated as (1/9) * 100 = 11.11.
user1 is sorted in ascending order.

## Solutions

• # Write your MySQL query statement below
WITH
F AS (
SELECT * FROM Friends
UNION
SELECT user2, user1 FROM Friends
),
T AS (SELECT count(DISTINCT user1) AS cnt FROM F)
SELECT DISTINCT
user1,
round(
(count(1) OVER (PARTITION BY user1)) * 100 / (SELECT cnt FROM T),
2
) AS percentage_popularity
FROM F
ORDER BY 1;