Calculate Salary Difference Using Self Join

Question

Find the difference between each employee's salary and their manager's salary.

Accepted Answer

```sql
SELECT 
    e.name AS employee_name, 
    e.salary - m.salary AS salary_difference
FROM employees e
JOIN employees m ON e.manager_id = m.id;
```

This query performs a self-join on the "employees" table to compare the "salary" of each employee with the "salary" of their respective manager, identified by the "manager_id" foreign key.