What was the longest carry for kevin clemens with under 31 yards total?
CREATE TABLE "running_backs" (
  "player" text,
  "car" real,
  "yards" real,
  "avg" real,
  "td_s" real,
  "long" real
);
SELECT MAX("long") FROM "running_backs" WHERE "player"='kevin clemens' AND "yards"<31;