Project Notes

Customers Who Never Order

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Description

tab: English
 
<p>Table: <code>Customers</code></p>
 
<pre>
+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| name        | varchar |
+-------------+---------+
id is the primary key (column with unique values) for this table.
Each row of this table indicates the ID and name of a customer.
</pre>
 
<p>&nbsp;</p>
 
<p>Table: <code>Orders</code></p>
 
<pre>
+-------------+------+
| Column Name | Type |
+-------------+------+
| id          | int  |
| customerId  | int  |
+-------------+------+
id is the primary key (column with unique values) for this table.
customerId is a foreign key (reference columns) of the ID from the Customers table.
Each row of this table indicates the ID of an order and the ID of the customer who ordered it.
</pre>
 
<p>&nbsp;</p>
 
<p>Write a solution to find all customers who never order anything.</p>
 
<p>Return the result table in <strong>any order</strong>.</p>
 
<p>The result format is in the following example.</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
 
<pre>
<strong>Input:</strong> 
Customers table:
+----+-------+
| id | name  |
+----+-------+
| 1  | Joe   |
| 2  | Henry |
| 3  | Sam   |
| 4  | Max   |
+----+-------+
Orders table:
+----+------------+
| id | customerId |
+----+------------+
| 1  | 3          |
| 2  | 1          |
+----+------------+
<strong>Output:</strong> 
+-----------+
| Customers |
+-----------+
| Henry     |
| Max       |
+-----------+
</pre>
 
 
 
---
 
[submissions](https://leetcode.com/problems/customers-who-never-order/submissions/) | [solutions](https://leetcode.com/problems/customers-who-never-order/solutions/)
 
 
tab: 中文
 
<p><code>Customers</code> 表：</p>
 
<pre>
+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| name        | varchar |
+-------------+---------+
在 SQL 中，id 是该表的主键。
该表的每一行都表示客户的 ID 和名称。</pre>
 
<p><code>Orders</code> 表：</p>
 
<pre>
+-------------+------+
| Column Name | Type |
+-------------+------+
| id          | int  |
| customerId  | int  |
+-------------+------+
在 SQL 中，id 是该表的主键。
customerId 是 Customers 表中 ID 的外键( Pandas 中的连接键)。
该表的每一行都表示订单的 ID 和订购该订单的客户的 ID。</pre>
 
<p>&nbsp;</p>
 
<p>找出所有从不点任何东西的顾客。</p>
 
<p>以 <strong>任意顺序</strong> 返回结果表。</p>
 
<p>结果格式如下所示。</p>
 
<p>&nbsp;</p>
 
<p><strong>示例 1：</strong></p>
 
<pre>
<b>输入：</b>
Customers table:
+----+-------+
| id | name  |
+----+-------+
| 1  | Joe   |
| 2  | Henry |
| 3  | Sam   |
| 4  | Max   |
+----+-------+
Orders table:
+----+------------+
| id | customerId |
+----+------------+
| 1  | 3          |
| 2  | 1          |
+----+------------+
<b>输出：</b>
+-----------+
| Customers |
+-----------+
| Henry     |
| Max       |
+-----------+</pre>
 
 
 
---
 
[提交记录](https://leetcode.cn/problems/customers-who-never-order/submissions/) | [题解](https://leetcode.cn/problems/customers-who-never-order/solution/)

Solutions & Notes

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