Heroes {hero_id, hero_name, villain_id, team_id}
Villains {villain_id, villain_name, team_id}
Teams {team_id, team_name, no_of_members}

CREATE TRIGGER team_no_inc
    BEFORE INSERT ON Heroes
    FOR EACH ROW
BEGIN
    UPDATE Teams SET no_of_members = no_of_members + 1
    FROM Heroes, Teams WHERE Teams.team_id = Heroes.team_id;
END;
.
RUN;