CREATE TABLE table_51988 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

On what date was a game played at MCG?
SELECT "Date" FROM table_51988 WHERE "Venue" = 'mcg'
SELECT "Date" FROM "table_51988" WHERE "Venue" = 'mcg'