You are given two tables: Customers and CustomerOrders. Write a SQL query to find all customers who have never placed any order. Return the customer id, name, and country, ordered by id. Table: Customers | Column Name | Type | Description | |-------------|---------|-----------------------| | id | INT | Primary key | | name | VARCHAR | Customer name | | country | VARCHAR | Customer country | Table: CustomerOrders | Column Name | Type | Description | |-------------|---------|---------------------------------| | id | INT | Primary key | | customer_id | INT | References Customers.id | | amount | DECIMAL | Order amount | | order_date | DATE | Date of order |

Customers Who Have Never Placed an Order

Preview mode. Log in to edit, run, submit, and save progress.

Medium

Description

You are given two tables: Customers and CustomerOrders. Write a SQL query to find all customers who have never placed any order. Return the customer id, name, and country, ordered by id. Table: Customers

Column Name	Type	Description
id	INT	Primary key
name	VARCHAR	Customer name
country	VARCHAR	Customer country

Table: CustomerOrders

Column Name	Type	Description
id	INT	Primary key
customer_id	INT	References Customers.id
amount	DECIMAL	Order amount
order_date	DATE	Date of order

Database Schema (Inferred)

Customers

Column Name	Example Value
id	1
name	Alice
country	US

CustomerOrders

Column Name	Example Value
id	1
customer_id	1
amount	200
order_date	2023-01-01

Example

Customers

id	name	country
1	Alice	US
2	Bob	UK
3	Carol	US
4	Dave	DE

CustomerOrders

id	customer_id	amount	order_date
1	1	200	2023-01-01
2	1	150	2023-02-01
3	3	300	2023-01-15

Output

id	name	country
2	Bob	UK
4	Dave	DE

Explanation:

Alice (id=1) and Carol (id=3) have orders. Bob and Dave have no orders and are returned.

Approach hint

Start with a simple approach, explain the trade-off, then move toward a cleaner or more scalable solution.

Common mistake

Skipping assumptions, edge cases, or trade-offs can make an otherwise good answer feel incomplete.