MySQL 5.7 - Inconsistent Results with LEFT JOIN and Filtering on the Joined Table
I'm experiencing unexpected behavior with a LEFT JOIN in MySQL 5.7 when filtering rows in the WHERE clause based on a column from the joined table. I have a query that fetches user data along with their associated orders, but I'm seeing inconsistent results due to the filtering condition being applied to the joined table's columns. Here's the query I'm using: ```sql SELECT u.id, u.name, o.order_id, o.amount FROM users u LEFT JOIN orders o ON u.id = o.user_id WHERE o.amount > 50; ``` I expect to see all users listed, including those without orders, but the filtering on `o.amount` seems to be excluding users with no orders from the results altogether. The output I get does not include users who have a `NULL` `order_id`, which is not what I was aiming for. When I run the query, I receive results that only show users with orders over 50, which suggests that the WHERE clause is treating NULL as false. I've tried moving the filtering condition to the ON clause: ```sql SELECT u.id, u.name, o.order_id, o.amount FROM users u LEFT JOIN orders o ON u.id = o.user_id AND o.amount > 50; ``` But this does not yield the desired results either, as it returns all users, but with `NULL` values in order details for those without qualifying orders. I am aware that according to SQL standards, the WHERE clause should filter out the results after the JOIN, but could someone explain how I might achieve my desired behavior of including all users regardless of whether they have qualifying orders? I'm also concerned about performance implications of these approaches, as the `users` table is quite large. Any insights or best practices would be greatly appreciated!