Name the highest Decile for roll more than 325 and area of warkworth
CREATE TABLE "rodney_local_board" (
  "name" text,
  "years" text,
  "area" text,
  "authority" text,
  "decile" real,
  "roll" real
);
SELECT MAX("decile") FROM "rodney_local_board" WHERE "roll">325 AND "area"='warkworth';