CREATE TABLE table_203_723 (id DECIMAL, "year" DECIMAL, "song" TEXT, "us hot 100" DECIMAL, "us msr" DECIMAL, "us a.c." DECIMAL, "can" DECIMAL, "uk singles" DECIMAL, "album" TEXT)

what was the top uk single on the firehouse album ?
SELECT "song" FROM table_203_723 WHERE "album" = 'firehouse' ORDER BY "uk singles" LIMIT 1
SELECT "song" FROM "table_203_723" WHERE "album" = 'firehouse' ORDER BY "uk singles" NULLS FIRST LIMIT 1