Debug: Duplicate Rows After CTE Join

Fix overcount caused by joining non-aggregated CTE output. WITH customer_orders AS (SELECT customer_id, total_amount FROM orders) SELECT c.id, SUM(co.total_amount) AS total_spend FROM customers c JOIN customer_orders co ON c.id = co.customer_id JOIN orders o ON c.id = o.customer_id GROUP BY c.id;

customers(id), orders(customer_id, total_amount)