Create 1729. Find Followers Count.sql

Co-Authored-By: Antim-IWP <[email protected]>

Author: iamAntimPal

1729. Find Followers Count.sql

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+1729. Find Followers Count
+
++-------------+------+
+| Column Name | Type |
++-------------+------+
+| user_id     | int  |
+| follower_id | int  |
++-------------+------+
+(user_id, follower_id) is the primary key (combination of columns with unique values) 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 a solution that will, for each user, return the number of followers.
+
+Return the result table ordered by user_id in ascending order.
+
+The 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}
+
+
+# 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;