<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Write a SQL query to count the total number of customers who haven't placed an order yet.
Table Name: customers<|im_end|>
<|im_start|>assistant
SELECT COUNT(*)
FROM customers
WHERE id NOT IN (SELECT customer_id FROM orders);<|im_end|>
