Data Axle needs a department-level compensation report. Write a PostgreSQL query that returns every employee whose salary equals the highest non-null salary in their department.
| Column | Type | Description |
|---|---|---|
| department_idPK | INTEGER | Unique department identifier |
| department_name | VARCHAR(100) | Department name |
| Column | Type | Description |
|---|---|---|
| employee_idPK | INTEGER | Unique employee identifier |
| department_id | INTEGER | Referenced department identifier |
| employee_name | VARCHAR(100) | Employee full name |
| job_title | VARCHAR(100) | Employee job title |
| salary | NUMERIC(12,2) | Annual employee salary |