###HUMAN: For those employees who was hired before 2002-06-21, give me the comparison about the average of department_id over the job_id , and group by attribute job_id, show x-axis in descending order., ###ASSISTANT: SELECT JOB_ID, AVG(DEPARTMENT_ID) FROM employees WHERE HIRE_DATE < '2002-06-21' GROUP BY JOB_ID ORDER BY JOB_ID DESC