CREATE TABLE table_203_645 (id DECIMAL, "lower mississippi periods" TEXT, "lower yazoo phases" TEXT, "lower yazoo\ dates" TEXT, "tensas/natchez phases" TEXT, "cahokia phases" TEXT, "cahokia dates" TEXT, "ohio/miss. river\ confluence phases" TEXT, "ohio/miss. dates" TEXT)

what is the name of the last cahokia phase ?
SELECT "cahokia phases" FROM table_203_645 ORDER BY id DESC LIMIT 1
SELECT "cahokia phases" FROM "table_203_645" ORDER BY "id" DESC NULLS LAST LIMIT 1