[chorn]

sollte klappen:

<?php

$subjects = [
	'',
	'123',
	'123456789',
	'123456789,',
	'123456789,123',
	'123456789,123456789',
	'123456789,123456789,',
];
foreach($subjects as $subject){
	var_dump(preg_match('`^([0-9]{9},)+$`', $subject, $matches));
	var_dump($matches);
}