Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_10592536_8 (date_of_appointment VARCHAR, date_of_vacancy VARCHAR)

### Question ###
What is the date of appointment when the date of vacancy is 21 december 2007?

### Accurate SQL ###

SELECT date_of_appointment FROM table_10592536_8 WHERE date_of_vacancy = "21 December 2007"