display the average salary of employees for each department who gets a commission percentage.
SELECT department_id ,  AVG(salary) FROM employees WHERE commission_pct != "null" GROUP BY department_id
SELECT department_id ,  AVG(salary) FROM employees WHERE commission_pct != "null" GROUP BY department_id
[{'DEPARTMENT_ID': 0, 'AVG(salary)': 7000.0}, {'DEPARTMENT_ID': 10, 'AVG(salary)': 4400.0}, {'DEPARTMENT_ID': 20, 'AVG(salary)': 9500.0}, {'DEPARTMENT_ID': 30, 'AVG(salary)': 4150.0}, {'DEPARTMENT_ID': 40, 'AVG(salary)': 6500.0}, {'DEPARTMENT_ID': 50, 'AVG(salary)': 3475.5555555555557}, {'DEPARTMENT_ID': 60, 'AVG(salary)': 5760.0}, {'DEPARTMENT_ID': 70, 'AVG(salary)': 10000.0}, {'DEPARTMENT_ID': 80, 'AVG(salary)': 8955.882352941177}, {'DEPARTMENT_ID': 90, 'AVG(salary)': 19333.333333333332}, {'DEPARTMENT_ID': 100, 'AVG(salary)': 8600.0}, {'DEPARTMENT_ID': 110, 'AVG(salary)': 10150.0}]