CREATE TABLE table_27683516_3 (team VARCHAR2, date_of_vacancy VARCHAR2)

How many dates of vacancy were on 30 october 2010?
SELECT COUNT(team) FROM table_27683516_3 WHERE date_of_vacancy = "30 October 2010"
SELECT COUNT("team") FROM "table_27683516_3" WHERE "30 October 2010" = "date_of_vacancy"