183. Customers Who Never Order

Description

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

Constraints

Approach

Links

• GeeksforGeeks

• Leetcode

• ProgramCreek

• YouTube

Examples

Example 1

Input:

{"headers": {"Customers": ["Id", "Name"], "Orders": ["Id", "CustomerId"]}, "rows": {"Customers": [[1, "Joe"], [2, "Henry"], [3, "Sam"], [4, "Max"]], "Orders": [[1, 3], [2, 1]]}}

Output:

{"headers": ["Customers"], "values": [["Henry"], ["Max"]]}

Solutions

Solution 1

# MySQL query statement

SELECT Name AS 'Customers'
FROM Customers
WHERE Id NOT IN (SELECT CustomerId FROM ORDERS)

Follow up