Unexpected NULL values in MySQL JOIN results when using LEFT JOIN with GROUP BY
I'm building a feature where I'm working with an scenario with MySQL where I'm using a `LEFT JOIN` in combination with `GROUP BY`, and I'm unexpectedly getting `NULL` values in my results. My tables are structured as follows: - `orders`: stores order details with columns `order_id`, `customer_id`, and `amount`. - `customers`: stores customer details with columns `customer_id` and `customer_name`. Here’s the query I’m using: ```sql SELECT c.customer_id, c.customer_name, SUM(o.amount) AS total_amount FROM customers c LEFT JOIN orders o ON c.customer_id = o.customer_id GROUP BY c.customer_id, c.customer_name; ``` The intention of this query is to get a list of customers along with the sum of their orders. However, for some customers who have never placed an order, I’m getting `NULL` for `total_amount` instead of `0`. I expected customers without orders to show `0` for their total amount. I’ve tried using `COALESCE` like this: ```sql SELECT c.customer_id, c.customer_name, COALESCE(SUM(o.amount), 0) AS total_amount FROM customers c LEFT JOIN orders o ON c.customer_id = o.customer_id GROUP BY c.customer_id, c.customer_name; ``` But I'm still seeing `NULL` values in the result. I also confirmed that there are indeed customers without orders in the `customers` table. I’m currently running MySQL version 8.0.26. Is there something I’m missing in my query, or is there a better way to handle this situation to ensure I get `0` for customers without any orders? I'm developing on macOS with Sql. Any ideas how to fix this?