Answer 1

function generatePIN($length = 8) {
$chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
$count = mb_strlen($chars);

for ($i = 0, $result = ''; $i < $length; $i++) {
$index = rand(0, $count - 1);
$result .= mb_substr($chars, $index, 1);
}

return $result;
}