CREATE TABLE table_name_4 (date_of_vacancy VARCHAR(255), date_of_appointment VARCHAR(255), manner_of_departure VARCHAR(255), position_in_table VARCHAR(255))
what is the date of vacancy when the manner of departure is contract terminated, the position in table is 23rd and the date of appointment is 31 december 2008?
    
SQL: SELECT date_of_vacancy FROM table_name_4 WHERE manner_of_departure = "contract terminated" AND position_in_table = "23rd" AND date_of_appointment = "31 december 2008"