- SQL Schema
Create table If Not Exists Customer (id int, name varchar(25), referee_id int)
Truncate table Customer
insert into Customer (id, name, referee_id) values ('1', 'Will', 'None')
insert into Customer (id, name, referee_id) values ('2', 'Jane', 'None')
insert into Customer (id, name, referee_id) values ('3', 'Alex', '2')
insert into Customer (id, name, referee_id) values ('4', 'Bill', 'None')
insert into Customer (id, name, referee_id) values ('5', 'Zack', '1')
insert into Customer (id, name, referee_id) values ('6', 'Mark', '2')
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<>2 or referee_id is null;