我想在浏览器上打印出打印语句。我试过但代码没有打印出来

Question

我想在浏览器上打印出打印语句。我试过但代码没有打印出来。请帮我解释一下代码。

<?php
$user_name = "root";
$password = "";
$database = "addressbook";
$server = "127.0.0.1";

$db_handle = @mysql_connect($server, $user_name, $password);
$db_found = mysql_select_db($database, $db_handle);
print("Connection to the server opened"."<br>");

if ($db_found) {
print "Database found";
$SQL = "SELECT * FROM tb_address_book";
$result = mysql_query($SQL);

while ($db_field = mysql_fetch_assoc($result)) {
print $db_field['ID']."<br>";
print $db_field['First_Name']."<br>";
print $db_field['Surname']."<br>";
print $db_field['Address']."<br>";
}

mysql_close($db_handle);

}else {
print "Database not found";
mysql_close($db_handle);
}
?>