How to resolve unexpected NULL values in SQLite during LEFT JOIN with multiple conditions?
After trying multiple solutions online, I still can't figure this out. I've looked through the documentation and I'm still confused about I'm working on a SQLite 3.34.1 project where I need to fetch employee details along with their department information... However, I'm encountering unexpected NULL values in the results when performing a LEFT JOIN on two tables with multiple join conditions. My query looks like this: ```sql SELECT e.id, e.name, d.department_name FROM employees e LEFT JOIN departments d ON e.department_id = d.id AND e.is_active = 1; ``` The intention is to retrieve all active employees along with their corresponding department names, but it seems that I'm getting rows with NULL department names even when I expect matches. I've verified that the `department_id` column in the `employees` table has valid values that exist in the `departments` table. To troubleshoot, I simplified the JOIN condition to just `e.department_id = d.id` and confirmed that it returns the expected results. However, adding the additional condition `AND e.is_active = 1` filters out records I was expecting to see. I also confirmed that `is_active` is set correctly for existing employees. What could be causing these NULL values to appear? Is there a better way to structure this JOIN to avoid these issues? I also tried using a subquery instead of a LEFT JOIN: ```sql SELECT e.id, e.name, (SELECT d.department_name FROM departments d WHERE e.department_id = d.id) AS department_name FROM employees e WHERE e.is_active = 1; ``` While this approach works, it is significantly slower on larger datasets. Any advice on how to effectively prevent these unexpected NULLs while maintaining performance would be greatly appreciated! My development environment is Windows. Am I missing something obvious? My development environment is Linux. Is there a better approach?