UPDATE bb_players SET
    bat_throw_type='batLR',
    firstname=(SELECT s.firstname FROM bb_player_names s
           WHERE s.bb_countries_id=nationality
           OFFSET random()*10 LIMIT 1),
    surname=(SELECT s.surname FROM bb_player_surnames s
           WHERE s.bb_countries_id=nationality
           OFFSET random()*10 LIMIT 1),
    age=18,
    years_left=3
WHERE is_bat='true' AND (years_left=1 OR retirement_age=age);