Leetcode 183. Customers Who Never Order

183. Customers Who Never Order

Total Accepted: 22007 Total Submissions: 68771 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       |+-----------+

思路：

寻找Customers中没有在Orders中出现的即可。关键字：not in

# Write your MySQL query statement belowselect a.name as 'Customers' from Customers awhere a.id not in (select customerid from Orders);