MySQL query with GROUP BY and ORDER BY giving incorrect row ordering
I'm getting frustrated with I'm migrating some code and I'm having a hard time understanding I'm experimenting with I tried several approaches but none seem to work... I'm working with an scenario with a MySQL query where I'm trying to group results by a `category_id` and order them by the `created_at` timestamp within each category. However, the results are not being ordered correctly as expected. I'm using MySQL version 8.0.25. Here's the query I'm currently using: ```sql SELECT category_id, COUNT(*) AS item_count, MAX(created_at) AS last_created FROM items GROUP BY category_id ORDER BY last_created DESC; ``` The intention is to return the categories in descending order based on the latest `created_at` timestamp of any item within each category. However, the results seem to be sorted randomly, and I frequently see categories that should come later in the order appearing before others. I've tried implementing a subquery to first get the `last_created` timestamp and then order by that, but it didn’t resolve the question. Here’s what that looked like: ```sql SELECT category_id, item_count, last_created FROM ( SELECT category_id, COUNT(*) AS item_count, MAX(created_at) AS last_created FROM items GROUP BY category_id ) AS grouped_items ORDER BY last_created DESC; ``` This still gives me the same unexpected order. I also checked for any indexes on the `created_at` column, and there’s an index present but it doesn't seem to help. I suspect it might have something to do with how MySQL is handling the ordering in conjunction with GROUP BY. Any insights into what could be going wrong, or how I could achieve the desired ordering would be greatly appreciated! How would you solve this? This is part of a larger REST API I'm building. How would you solve this? This is part of a larger web app I'm building. What's the best practice here? This is my first time working with Sql stable. I'd really appreciate any guidance on this.