CREATE TABLE table_204_400 (id DECIMAL, "district" DECIMAL, "senator" TEXT, "party" TEXT, "caucus" TEXT, "first elected" DECIMAL, "counties represented" TEXT)

who was the last sentor from erie ?
SELECT "senator" FROM table_204_400 WHERE "counties represented" = 'erie' ORDER BY id DESC LIMIT 1
SELECT "senator" FROM "table_204_400" WHERE "counties represented" = 'erie' ORDER BY "id" DESC NULLS LAST LIMIT 1