task: #584

Author: Ivanbyone

README.md

@@ -34,6 +34,7 @@ Useful for preparing for technical interviews and improving your SQL skills.
 
 ### Select
 
+- [584. Find Customer Referee](./leetcode/easy/584.%20Find%20Customer%20Referee.sql)
 - [595. Big Countries](./leetcode/easy/595.%20Big%20Countries.sql)
 - [1148. Article Views I](./leetcode/easy/1148.%20Article%20Views%20I.sql)
 - [1683. Invalid Tweets](./leetcode/easy/1683.%20Invalid%20Tweets.sql)
@@ -112,6 +113,7 @@ Useful for preparing for technical interviews and improving your SQL skills.
     - [197. Rising Temperature](./leetcode/easy/197.%20Rising%20Temperature.sql)
     - [511. Game Play Analysis 1](./leetcode/easy/511.%20Game%20Play%20Analysis%201.sql)
     - [577. Employee Bonus](./leetcode/easy/577.%20Employee%20Bonus.sql)
+    - [584. Find Customer Referee](./leetcode/easy/584.%20Find%20Customer%20Referee.sql)
     - [586. Customer Placing the Largest Number of Orders](./leetcode/easy/586.%20Customer%20Placing%20the%20Largest%20Number%20of%20Orders.sql)
     - [595. Big Countries](./leetcode/easy/595.%20Big%20Countries.sql)
     - [596. Classes With at Least 5 Students](./leetcode/easy/596.%20Classes%20With%20at%20Least%205%20Students.sql)

leetcode/easy/584. Find Customer Referee.sql

@@ -0,0 +1,25 @@
+/*
+Question 584. Find Customer Referee
+Link: https://leetcode.com/problems/find-customer-referee/description/?envType=problem-list-v2&envId=database
+
+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.
+*/
+
+SELECT name
+FROM customer
+WHERE referee_id <> 2 OR referee_id IS NULL