MySQL 8.0 - Unexpected NULL Values in Aggregate Functions with LEFT JOINs
I'm a bit lost with I'm getting frustrated with Hey everyone, I'm running into an issue that's driving me crazy. I've been struggling with this for a few days now and could really use some help. I'm working with an scenario with MySQL 8.0 where my query, which utilizes LEFT JOINs along with aggregate functions, is returning unexpected NULL values. My goal is to retrieve the total sales amount for each product, even if a product has no associated sales. The following query is what I've constructed: ```sql SELECT p.product_id, p.product_name, SUM(s.amount) AS total_sales FROM products p LEFT JOIN sales s ON p.product_id = s.product_id GROUP BY p.product_id, p.product_name; ``` While I expect the `total_sales` to show 0 for products without sales, it instead returns NULL for those cases. I've tried using `COALESCE` to convert NULL to 0: ```sql SELECT p.product_id, p.product_name, COALESCE(SUM(s.amount), 0) AS total_sales FROM products p LEFT JOIN sales s ON p.product_id = s.product_id GROUP BY p.product_id, p.product_name; ``` However, the result is still the same, and I still see NULL values for `total_sales`. I've also verified that there are indeed products without any entries in the `sales` table. Additionally, I checked for NULL amounts in the `sales` table, but all entries have valid positive values. Is there something I'm missing in my query formulation, or is there a specific behavior in MySQL 8.0 that I should be aware of? Any insights would be greatly appreciated! I'm working with Sql in a Docker container on CentOS. I'm on Ubuntu 22.04 using the latest version of Sql. Hoping someone can shed some light on this. I've been using Sql for about a year now. Any pointers in the right direction?