php如何避免1970前时间时间戳失效了

mysql_connect();
$d1 = '1901-01-12';
$d2 = '1885-11-25';
$rs = mysql_query("select TO_DAYS('$d1')-TO_DAYS('$d2')");
list($t) = mysql_fetch_row($rs);
echo $t;

------解决方案--------------------


PHP code
date_default_timezone_set('Asia/Hong_Kong');

$datetime1 = new DateTime('1885-11-25');
$datetime2 = new DateTime('1901-01-12');

$interval = $datetime1->diff($datetime2);
print_r($interval);