leetcode 183. Customers Who Never Order

Posted 2020-06-16

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183. Customers Who Never Order

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Question

Total Accepted: 14489 Total Submissions: 43113 Difficulty: Easy

 

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       |
+-----------+

 

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转载题解：

http://my.oschina.net/liusicong/blog/375039?p={{currentPage+1}}

 

 

1 # Write your mysql query statement below
2 select Name from Customers c
3     where c.Id not in
4         (select CustomerId from Orders o)

 

1 # Write your MySQL query statement below
2 select Name from 
3     Customers c left join Orders o
4         on c.Id = o.CustomerId
5             where o.Id is NULL 
6