0183._Customers_Who_Never_Order.md

183. Customers Who Never Order

难度: Easy

刷题内容

原题连接

• https://leetcode.com/problems/customers-who-never-order/

内容描述

SQL Schema
Suppose that a website contains two tables, the Customers table and the Orders table. Write a SQL query to find all customers who never order anything.

Table: Customers.

+----+-------+
| Id | Name  |
+----+-------+
| 1  | Joe   |
| 2  | Henry |
| 3  | Sam   |
| 4  | Max   |
+----+-------+
Table: Orders.

+----+------------+
| Id | CustomerId |
+----+------------+
| 1  | 3          |
| 2  | 1          |
+----+------------+
Using the above tables as example, return the following:

+-----------+
| Customers |
+-----------+
| Henry     |
| Max       |
+-----------+

解题方案

思路 1

select c.Name as Customers from Customers c where c.Id not in 
                            (select CustomerId from Orders o)