MySQL 8.0: Unexpected NULL results when using COALESCE with LEFT JOIN
I'm prototyping a solution and I've searched everywhere and can't find a clear answer... I'm reviewing some code and I'm relatively new to this, so bear with me. I'm working on a project and hit a roadblock... I'm working with unexpected NULL results when using the `COALESCE` function in conjunction with a `LEFT JOIN` in MySQL 8.0. I have two tables, `orders` and `customers`, where `orders` has a foreign key referencing `customers`. The scenario arises when I try to retrieve the order details along with customer names, defaulting to 'Unknown' if a customer does not exist. Here’s the query I’m using: ```sql SELECT o.order_id, COALESCE(c.name, 'Unknown') AS customer_name FROM orders o LEFT JOIN customers c ON o.customer_id = c.id; ``` However, this returns `NULL` for `customer_name` instead of 'Unknown' when there are orders without a corresponding customer. I’ve tried different variations of the query, including placing `COALESCE` directly in the `SELECT` clause and using `IFNULL`, but the outcome remains the same. I've also checked that the `customer_id` column is indeed nullable and that there are orders without matching customer records. The version of MySQL I'm using is 8.0.23. Furthermore, I attempted to run the query without the `COALESCE` function to see if it returns the expected rows, and it does, showing the correct order IDs with NULL in the `customer_name` field where applicable. I’m not sure if there’s a hidden configuration or compatibility scenario at play here, or if I’m overlooking something in my query logic. Any suggestions on how to resolve this would be greatly appreciated! Any ideas what could be causing this? This is part of a larger service I'm building. Has anyone else encountered this? For reference, this is a production REST API. What are your experiences with this? This is happening in both development and production on CentOS. Any ideas how to fix this? I'm developing on Windows 11 with Sql. Could someone point me to the right documentation?