instruction: For those employees who was hired before 2002-06-21, find hire_date and the sum of manager_id bin hire_date by time, and visualize them by a bar chart, and I want to show by the total number of manager id from high to low.
response: SELECT HIRE_DATE, SUM(MANAGER_ID) FROM employees WHERE HIRE_DATE < '2002-06-21' ORDER BY SUM(MANAGER_ID) DESC