编写解决方案，对于每一个用户，返回该用户的关注者数量。 #按 user_id 的顺序返回结果表

题目链接：

https://leetcode.cn/problems/find-followers-count/description/

建表插入语句：

Create table If Not Exists Followers(user_id int, follower_id int)
Truncate table Followers
insert into Followers (user_id, follower_id) values ('0', '1')
insert into Followers (user_id, follower_id) values ('1', '0')
insert into Followers (user_id, follower_id) values ('2', '0')
insert into Followers (user_id, follower_id) values ('2', '1')

画图分析：

代码实现：

select user_id,
       count(follower_id)  as followers_count 
from Followers group by user_id order by user_id;