Anti Join Pattern

How can we find customers who have never placed an order?

Advanced⏱ 3 Minutes⭐ 1010 XP

🤔 THE QUESTION

How can we find customers who have never placed an order?

💡 WHAT IS IT?

The Anti Join pattern uses LEFT JOIN ... WHERE right_key IS NULL to find entities with zero matching activity.

🎯 WHAT IS IT USED FOR?

Inactive user marketing, zero-purchase customer outreach, abandoned account tracking.

💻 EXAMPLE

SELECT c.customer_name
FROM customers c
LEFT JOIN orders o
ON c.customer_id = o.customer_id
WHERE o.order_id IS NULL;

Practice typing production-grade SQL code for Anti Join Pattern.