Schema: CREATE TABLE table_name_4 (date_of_vacancy VARCHAR, date_of_appointment VARCHAR, manner_of_departure VARCHAR, position_in_table VARCHAR)
Question: 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"