1729 Find Followers Count.md

1729. Find Followers Count

https://leetcode.cn/problems/find-followers-count/
Table: Followers

Column Name	Type
user_id	int
follower_id	int

(user_id, follower_id) is the primary key for this table.
This table contains the IDs of a user and a follower in a social media app where the follower follows the user.

Write an SQL query that will, for each user, return the number of followers.
Return the result table ordered by user_id.
The query result format is in the following example.

Example 1:

Input:
Followers table:

user_id	follower_id
0	1
1	0
2	0
2	1

Output:

user_id	followers_count
0	1
1	1
2	2

Explanation:
The followers of 0 are {1}
The followers of 1 are {0}
The followers of 2 are {0,1}

solution

# Write your MySQL query statement below
SELECT
    user_id,
    COUNT(follower_id) AS followers_count
FROM Followers
GROUP BY user_id
ORDER BY user_id