CREATE TABLE table_24912 ("Team" TEXT, "Outgoing manager" TEXT, "Manner of departure" TEXT, "Date of vacancy" TEXT, "Replaced by" TEXT, "Date of appointment" TEXT)

Who was the replacement manager for the vacancy of 12 Dec 2009?
SELECT "Replaced by" FROM table_24912 WHERE "Date of vacancy" = '12 Dec 2009'
SELECT "Replaced by" FROM "table_24912" WHERE "Date of vacancy" = '12 Dec 2009'