MySQL query with subquery and LIMIT returns unexpected results in Laravel 9
I'm having trouble with I'm stuck on something that should probably be simple..... I've been banging my head against this for hours. I'm working on a Laravel 9 application where I need to retrieve the most recent orders for each customer. I've structured my query to use a subquery with a LIMIT clause, but I'm working with unexpected results. It seems like I'm not getting the correct latest order for each customer. Here's the query I'm currently using: ```sql SELECT * FROM orders o WHERE o.id IN ( SELECT id FROM orders WHERE customer_id = o.customer_id ORDER BY created_at DESC LIMIT 1 ) ORDER BY customer_id; ``` I've tried running the subquery independently, and it returns what I expect when I specify a single customer ID. However, when used in the main query, it gives me multiple rows for some customers instead of just the latest one. Additionally, I verified that the `created_at` field is correctly populated and indexed. To troubleshoot, I even tried using a JOIN instead: ```sql SELECT o.* FROM orders o JOIN ( SELECT customer_id, MAX(created_at) as latest_order_date FROM orders GROUP BY customer_id ) latest ON o.customer_id = latest.customer_id AND o.created_at = latest.latest_order_date; ``` This approach gives me the correct results, but it's noticeably slower, especially with larger datasets. I'm wondering if there's a more efficient way to achieve this without sacrificing performance. Has anyone else encountered this scenario or have suggestions for optimizing my query? Any insights would be greatly appreciated! Am I missing something obvious? I'm working on a API that needs to handle this. I'm working in a CentOS environment. What am I doing wrong? Any feedback is welcome!