1. 程式人生 > >183. Customers Who Never Order--solution

183. Customers Who Never Order--solution

any and -- rom eve sam sele body ever

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


My solution:

SELECT A.Name as Customers from Customers A
LEFT JOIN Orders B on A.Id = B.CustomerId
WHERE B.CustomerId is NULL;

183. Customers Who Never Order--solution