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Customers Who Never Ordered
Amazon's CRM team wants to re-engage registered buyers who've created an account but never placed an order — prime targets for dormant-user email campaigns. Write a SQL query that returns the customer name for every such account. Order by name ascending. This anti-join pattern (LEFT JOIN + NULL filter, or NOT IN / NOT EXISTS) is a bread-and-butter Amazon analyst question — the same logic powers every re-activation campaign.
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Schema
customers
| customer_id | name | signup_date | membership | total_orders | |
|---|---|---|---|---|---|
| 1 | John Smith | john.smith@email.com | 2023-01-15 | Gold | 15 |
| 2 | Emma Wilson | emma.wilson@email.com | 2023-03-20 | Silver | 8 |
| 3 | Michael Brown | michael.brown@email.com | 2023-02-10 | Gold | 12 |
orders
| order_id | customer_id | product | category | quantity | price | total | order_date | country | status |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1 | Laptop Pro | Electronics | 1 | 1299.99 | 1299.99 | 2024-01-15 | USA | completed |
| 2 | 2 | Wireless Mouse | Electronics | 2 | 49.99 | 99.98 | 2024-01-16 | Canada | completed |
| 3 | 3 | Office Chair | Furniture | 1 | 349.99 | 349.99 | 2024-01-17 | USA | completed |
Expected output: Names of buyers with zero marketplace orders
Hint
Concepts
SELECT LEFT JOIN WHERE LEFT JOIN / NOT IN
Practise the topic: SQL practice questions · JOIN practice
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