instruction: For those employees who was hired before 2002-06-21, find hire_date and the average of department_id bin hire_date by time, and visualize them by a bar chart, and display by the y-axis from high to low.
response: SELECT HIRE_DATE, AVG(DEPARTMENT_ID) FROM employees WHERE HIRE_DATE < '2002-06-21' ORDER BY AVG(DEPARTMENT_ID) DESC