CREATE TABLE table_57501 ("City of license/market" TEXT, "Station" TEXT, "Channel TV  (  RF  ) " TEXT, "Year of affiliation" FLOAT, "Year of disaffiliation" FLOAT)

What is the earliest year of disaffiliation of a CHCH-TV station, licensed in Hamilton, Ontario?
SELECT MIN("Year of disaffiliation") FROM table_57501 WHERE "City of license/market" = 'hamilton, ontario'
SELECT MIN("Year of disaffiliation") FROM "table_57501" WHERE "City of license/market" = 'hamilton, ontario'