CREATE TABLE table_204_56 (id DECIMAL, "year" DECIMAL, "song" TEXT, "us r&b" DECIMAL, "us rap" DECIMAL, "album" TEXT)

which song has the most in us r & b ?
SELECT "song" FROM table_204_56 ORDER BY "us r&b" LIMIT 1
SELECT "song" FROM "table_204_56" ORDER BY "us r&b" NULLS FIRST LIMIT 1