CREATE TABLE table_204_13 (id DECIMAL, "finished" TEXT, "post" DECIMAL, "horse" TEXT, "jockey" TEXT, "trainer" TEXT, "owner" TEXT, "time / behind" TEXT)

name of horse that came in last in the 1997 kentucky derby
SELECT "horse" FROM table_204_13 ORDER BY "finished" DESC LIMIT 1
SELECT "horse" FROM "table_204_13" ORDER BY "finished" DESC NULLS LAST LIMIT 1