when the points for is 139 is points difference?
CREATE TABLE "2008_2009_table" (
  "club" text,
  "played" text,
  "won" text,
  "drawn" text,
  "lost" text,
  "points_for" text,
  "points_against" text,
  "points_difference" text,
  "bonus_points" text,
  "points" text
);
SELECT COUNT("points_difference") FROM "2008_2009_table" WHERE "points_for"='139';