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 |
+-----------+
此題，竟然一時間沒想到如何合理的解決方案，主要是有較長的時間沒有使用IN與NOT IN.
SQL也是一個手熟的活，需要經常鍛煉，以下是解題答案：
# Write your MySQL query statement below
SELECT Customers.Name AS Customers
FROM Customers
WHERE Customers.Id NOT IN (SELECT CustomerId FROM Orders)
PS:
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標籤：MySQL