Write a function to identify the fourth highest salary in an employee database.
Assume that "fourth highest" means the fourth-highest distinct non-NULL salary. Return every employee who earns that salary. Employees with NULL salaries must not be considered.
employee_id, employee_name, and salarysalary descending, then employee_id ascending| Column | Type | Description |
|---|---|---|
| employee_idPK | INTEGER | Unique employee identifier |
| employee_name | VARCHAR(100) | Employee's full name |
| salary | NUMERIC(12,2) | Employee's salary |