8/5 每日一題(MYSQL 返回所有不是ID 2推薦的客戶)

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 | 

+------+ 

# Write your MySQL query statement below

SELECT name

#選擇輸出name欄位

FROM Customer

#從Customer表

WHERE referee_id !=2 or referee_id IS null;

#返回所有不是由referee_id=2推薦的 和沒有人推薦的客戶