For the following examples for the aggregate methods, assume a teradataml DataFrame "df" is created from a Vantage table "employee_info", using command:
>>> df = DataFrame("employee_info")
Enter the df to display the DataFrame.
>>> df first_name marks dob joined_date employee_no 100 abcd None None None 101 abcde None None 1902-05-12 112 None None None 2018-05-12