PostgreSQL - Unexpected NULL values in LEFT JOIN when filtering on related table columns
Could someone explain After trying multiple solutions online, I still can't figure this out... I'm working with an scenario with a LEFT JOIN in PostgreSQL 13.3 where I expect to see matching records from the left table but am getting NULL values instead. The query is designed to pull data from two tables: `orders` and `customers`. Here's the SQL I'm using: ```sql SELECT o.id, o.amount, c.name FROM orders o LEFT JOIN customers c ON o.customer_id = c.id WHERE c.status = 'active'; ``` I expect to retrieve all orders regardless of whether the customer exists or is active, but when I filter on `c.status`, it seems to exclude orders from customers who might not meet that criteria, resulting in NULLs for `c.name` even when there are orders present. I've tried removing the `WHERE` clause and replacing it with a condition in the `ON` clause: ```sql SELECT o.id, o.amount, c.name FROM orders o LEFT JOIN customers c ON o.customer_id = c.id AND c.status = 'active'; ``` However, this returned an unexpected number of rows where the customer names are NULL, as it seems to completely filter out inactive customers. Is there a way to correctly structure the query so that I can see all orders with customers marked as active while still returning NULL for the customers that don't exist or are inactive? It seems like a logical oversight on my part, but I need to pinpoint what I'm doing wrong. Any help would be greatly appreciated! For context: I'm using Sql on macOS. How would you solve this? For context: I'm using Sql on Linux. What am I doing wrong? My development environment is Ubuntu 22.04. I'd be grateful for any help.