MySQL 5.7: LEFT JOIN with WHERE clause filters out results unexpectedly
I'm wondering if anyone has experience with I've been struggling with this for a few days now and could really use some help. I'm wondering if anyone has experience with I'm working on a project and hit a roadblock..... I'm working on a project and hit a roadblock. I'm working with a perplexing scenario while trying to filter results in a LEFT JOIN query using MySQL 5.7... I have two tables: `orders` and `customers`. The `orders` table has a foreign key `customer_id` that references the `customers` table. My intention is to get all the orders along with customer details, even if some orders don't have an associated customer. However, when I apply a filter on the `customers` table in the WHERE clause, I'm getting no results even though I expect some orders to show up. Here's the query I'm using: ```sql SELECT o.order_id, o.order_date, c.customer_name FROM orders o LEFT JOIN customers c ON o.customer_id = c.customer_id WHERE c.status = 'active'; ``` With this query, I expected to see all orders, irrespective of the customer status, but it seems like no orders are returned when there are customers with a status other than 'active'. I have tried moving the filter into the ON clause as well: ```sql SELECT o.order_id, o.order_date, c.customer_name FROM orders o LEFT JOIN customers c ON o.customer_id = c.customer_id AND c.status = 'active'; ``` This adjustment gave me the correct results, but I want to understand why the original query behaved this way. Is there a specific reason why filtering in the WHERE clause causes the LEFT JOIN to behave like an INNER JOIN in this case? How can I effectively filter while still retaining all left join records? Any insights would be appreciated! I'm working on a service that needs to handle this. I'm working on a service that needs to handle this. I'd really appreciate any guidance on this. I'd really appreciate any guidance on this. I appreciate any insights! Thanks in advance! I'm working in a Debian environment. Any feedback is welcome!