👀 Views: 99 💬 Answers: 1 📅 Created: 2025-06-22

mysql sql aggregates SQL

I'm sure I'm missing something obvious here, but This might be a silly question, but I'm running into an scenario where I'm using a `CASE` statement within an aggregate function, and it's not returning the results I expect when NULL values are involved..... My table `sales` has columns `id`, `amount`, and `category`. I want to calculate the total sales amount for each category, but I'm handling the case where `amount` could be NULL. Here’s the query I’m currently using: ```sql SELECT category, SUM(CASE WHEN amount IS NOT NULL THEN amount ELSE 0 END) AS total_sales FROM sales GROUP BY category; ``` While I thought this would correctly sum up the sales for each category, I'm often getting a total of zero for some categories that do have relevant entries. After checking the data, it seems like there's an scenario when the `amount` values are NULL in a way that I didn't anticipate. I also tried using `IFNULL(amount, 0)` but that didn't change the results. Additionally, I verified that the `amount` column is defined as `DECIMAL(10,2)` and contains both NULL and non-NULL entries. Is there something subtle I’m missing with how MySQL handles NULLs in this context? Any insights would be greatly appreciated. My development environment is Linux. Is there a better approach? This issue appeared after updating to Sql stable. Any examples would be super helpful. This is for a service running on Debian. What am I doing wrong? Is there a better approach? For context: I'm using Sql on macOS. Thanks, I really appreciate it!