What does the following query pattern accomplish? SELECT e.* FROM employees e LEFT JOIN managers m ON e.id = m.employee_id WHERE m.employee_id IS NULL

Question

SQL Fundamentals — Hard

What does the following query pattern accomplish? SELECT e.* FROM employees e LEFT JOIN managers m ON e.id = m.employee_id WHERE m.employee_id IS NULL

Accepted Answer

The query pattern SELECT e.* FROM employees e LEFT JOIN managers m ON e.id = m.employee_id WHERE m.employee_id IS NULL uses the anti-join pattern to return employees who are not managers. This is achieved by filtering out rows where the employee_id in the managers table is NULL.