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MySQL query using COALESCE() with multiple JOINs returns unexpected NULLs

👀 Views: 265 đŸ’Ŧ Answers: 1 📅 Created: 2025-06-08
MySQL COALESCE JOIN SQL GROUP BY

I'm following best practices but I'm learning this framework and I'm learning this framework and I'm integrating two systems and I'm working on a project and hit a roadblock. I'm working on a MySQL 8.0 query that involves multiple JOINs, and I'm running into an scenario where the `COALESCE()` function is not returning the expected results. I have three tables: `users`, `orders`, and `payments`. The goal is to retrieve a list of users with their last order date and payment status. However, when there are no orders or payments for a user, I expect `NULL` values to be replaced by 'No Orders' or 'No Payments', but I'm getting NULLs instead. Here's the SQL I wrote: ```sql SELECT u.id, u.name, COALESCE(MAX(o.order_date), 'No Orders') AS last_order_date, COALESCE(MAX(p.status), 'No Payments') AS payment_status FROM users u LEFT JOIN orders o ON u.id = o.user_id LEFT JOIN payments p ON o.id = p.order_id GROUP BY u.id; ``` When I run this query, users without orders or payments are still showing NULL in the columns for `last_order_date` and `payment_status`. I've tried wrapping the `COALESCE()` function around the entire `SELECT` clause and even experimented with changing the `LEFT JOIN` to an `INNER JOIN`, but I still get NULLs. I also verified that there are indeed users without any orders or payments in the database. Is there a specific behavior of `COALESCE()` that I might be missing, or is there a better approach to achieve what I want? Any help would be greatly appreciated! Any help would be greatly appreciated! I'm working in a Windows 10 environment. Has anyone else encountered this? What am I doing wrong? For reference, this is a production desktop app. Is there a better approach?