@@ -1,2 +1,55 @@
+-- Problem:
+
+/*
+Table: Customer
+
++-------------+---------+
+| Column Name | Type |
++-------------+---------+
+| id | int |
+| name | varchar |
+| referee_id | int |
++-------------+---------+
+In SQL, id is the primary key column for this table.
+Each row of this table indicates the id of a customer, their name, and the id of the customer who referred them.
+
+
+Find the names of the customer that are not referred by the customer with id = 2.
+
+Return the result table in any order.
+
+The result format is in the following example.
+
+
+
+Example 1:
+
+Input:
+Customer table:
++----+------+------------+
+| id | name | referee_id |
++----+------+------------+
+| 1 | Will | null |
+| 2 | Jane | null |
+| 3 | Alex | 2 |
+| 4 | Bill | null |
+| 5 | Zack | 1 |
+| 6 | Mark | 2 |
++----+------+------------+
+Output:
++------+
+| name |
++------+
+| Will |
+| Jane |
+| Bill |
+| Zack |
++------+
+*/
+
+-------------------------------------------------------------------------------
+
+-- Solution:
+
 SELECT name FROM Customer
 WHERE (referee_id IS NULL) OR (NOT referee_id = 2)