Name the years for porangahau school
CREATE TABLE "central_hawke_s_bay_district" (
  "name" text,
  "years" text,
  "gender" text,
  "area" text,
  "authority" text,
  "decile" real,
  "roll" real
);
SELECT "years" FROM "central_hawke_s_bay_district" WHERE "area"='porangahau' AND "name"='porangahau school';