CREATE TABLE table_28164986_4 (date_of_appointment VARCHAR, manner_of_departure VARCHAR, team VARCHAR)

when was the next coach appointed after niger tornadoes fired their coach?
SELECT date_of_appointment FROM table_28164986_4 WHERE manner_of_departure = "fired" AND team = "Niger Tornadoes"
SELECT "date_of_appointment" FROM "table_28164986_4" WHERE "Niger Tornadoes" = "team" AND "fired" = "manner_of_departure"