SELECT department_id ,  AVG(salary) FROM employees WHERE commission_pct != "null" GROUP BY department_id
What is the average salary of employees who have a commission percentage that is not null?
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 ! = value group by department_id
What is the average salary of employees who have a commission percentage that is not null ?