# 1a
$dbh->do(qq~INSERT INTO scores VALUES($userid, $score, NOW())~);
#1b
$dbh->do(qq~INSERT INTO scores VALUES(?, ?, NOW())~, undef, $userid, $score);

#2a
$dbh->do(qq~UPDATE scores SET score=? WHERE userid=?)~, undef, $new_score, $userid);
#2b
$dbh->do(qq~UPDATE scores SET score=$new_score WHERE userid=$userid)~);