MySQL 8.0: Strange behavior with GROUP_CONCAT and ORDER BY in subqueries
I'm attempting to set up I've been banging my head against this for hours. I'm relatively new to this, so bear with me... I'm learning this framework and I'm working on a project and hit a roadblock. I'm relatively new to this, so bear with me. I'm having a peculiar issue with MySQL 8.0 when using `GROUP_CONCAT` in a subquery that also uses `ORDER BY`. The goal is to retrieve a list of user emails grouped by their department, ordered by the most recent registration date. However, the order seems to be ignored in the final concatenated string. Here's the query I've constructed: ```sql SELECT d.department_name, (SELECT GROUP_CONCAT(u.email ORDER BY u.registration_date DESC) FROM users u WHERE u.department_id = d.id) AS emails FROM departments d; ``` When I execute this, the emails in the `emails` column are returned in a seemingly random order, rather than the expected descending order based on the `registration_date`. I've also tried using `GROUP BY` inside the subquery, but that didn't change the outcome. I verified that the `registration_date` values are correct and distinct among users, and I even ran the inner query independently to confirm it returns the expected ordered list of emails. Still, the final output doesn't reflect that order. Here's the output I get: ``` department_name | emails ----------------|---------------------------- HR | alice@example.com, bob@example.com Engineering | charlie@example.com, dave@example.com ``` The emails for HR should have been ordered with `bob@example.com` first, but they are not. Is there a known issue with `GROUP_CONCAT` and `ORDER BY` in subqueries in MySQL 8.0, or am I missing something in the query structure? Any guidance would be appreciated! What am I doing wrong? Any ideas what could be causing this? I'm working on a CLI tool that needs to handle this. What's the best practice here? Could this be a known issue? This is for a desktop app running on Ubuntu 22.04. Is this even possible? I've been using Sql for about a year now. Hoping someone can shed some light on this.