MySQL query using GROUP_CONCAT() not aggregating correctly with NULL values
I'm stuck on something that should probably be simple. I'm working on a MySQL 8.0 database, and I've encountered an scenario where the `GROUP_CONCAT()` function is not returning the expected results when there are NULL values in my dataset... I have a table `employees` structured like this: ```sql CREATE TABLE employees ( id INT PRIMARY KEY, name VARCHAR(100), department_id INT ); ``` I am trying to aggregate employee names by their department, but some employees don't belong to any department, resulting in their `department_id` being NULL. Here’s the query I’m currently using: ```sql SELECT department_id, GROUP_CONCAT(name) AS employee_names FROM employees GROUP BY department_id; ``` The output seems fine for departments with valid `department_id`s, but it's completely missing the NULL values. I expected to see a row with `NULL` for `department_id` and a concatenated list of names for those employees. Instead, that row isn't appearing at all. I tried using `COALESCE(department_id, 'No Department')` in my `SELECT` clause to handle NULLs: ```sql SELECT COALESCE(department_id, 'No Department') AS department_id, GROUP_CONCAT(name) AS employee_names FROM employees GROUP BY department_id; ``` However, this still doesn't return the NULL department employees. Am I missing something with how NULLs are handled in GROUP BY clauses in MySQL? What would be the best way to include employees with NULL `department_id` in my results? Any help would be appreciated! This is part of a larger CLI tool I'm building. Am I missing something obvious? My team is using Sql for this application. I'd be grateful for any help.