+/-
codice:
<?php
$conn = mysql_connect("localhost", "root", "") or die(mysql_error());
mysql_select_db("test") or die(mysql_error());
$sql = "SELECT * FROM tabella";
$rs = mysql_query($sql) or die(mysql_error());
$a = 0;
$b = 1;
$c = 1;
while ($row = mysql_fetch_array($rs)) {
    $file = 'file' . $c . '.txt';
    if ($a % 5 == 0) {
        $b = 1;
        if (isset($h)) {
            fclose($h);
        }
        $h = fopen($file, 'w');
        $c++;
    }
    $text = '&primo' . $b . '=' . $row[0] . '&secondo' . $b . '=' . $row[1] ."\r\n";
    fwrite($h, $text);
    $a++;
    $b++;
}
fclose($h);
echo 'finished';
?>