CREATE TABLE table_54421 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

What date did the Away team, North Melbourne, play Geelong?
SELECT "Date" FROM table_54421 WHERE "Away team" = 'north melbourne'
SELECT "Date" FROM "table_54421" WHERE "Away team" = 'north melbourne'