 how many clubs had a positive goal difference ?
CREATE TABLE table_203_145 (
    id number,
    "position" number,
    "club" text,
    "played" number,
    "points" text,
    "wins" number,
    "draws" number,
    "losses" number,
    "goals for" number,
    "goals against" number,
    "goal difference" number
)
SELECT COUNT("club") FROM table_203_145 WHERE "goals for" - "goals against" > 0