$re = '/,(?!\d+\))/m';
$str = 'Id uniqueidentifier null2,2version varchar(50) null,Modified datetime null,ModifiedBy uniqueidentifier null,Created datetime null,CreatedBy uniqueidentifier null,Folder_Id uniqueidentifier null,Currency_Id uniqueidentifier null,RefCurrency_Id uniqueidentifier null,ValidFrom datetime null,ValidTo datetime null,Rate decimal(28,18) null,';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php