Getting a blank page with PHP&MySQL

I'm getting a blank page with this code:

session_start();
include "config.php";
$af = $_GET['id'];
database_connect();
$query2 = "SELECT * FROM friends WHERE usr1 = '".$id."' AND usr2 = '".$af."'";
$result2 = mysql_query($query2) or die(mysql_error());
while ($row2 = mysql_fetch_assoc($result2)) {
if($row2['id']){
 echo "<script type='javascript'>alert('You are already friends with this person.');</script>";
 header('Location: profile.php?id="'.$af.'"');
}else{
    mysql_query("INSERT INTO friends (usr1, usr2)  
            VALUES ('".$id."', '".$af."')") or die(mysql_error());
            echo "<script type='javascript'>alert('You two are friends now!');</script>";
        header('Location: profile.php?id="'.$af.'"');
};
};

This is the config.php (i changed the variables here thoug开发者_开发知识库h)

$h = "localhost";    
$u = "user";      
$p = "pass";   
$d = "datab";  

$sql = 'SELECT id FROM craffyposts limit '.($page*$eachPage).','.$eachPage;

$sql_count = 'SELECT id FROM craffyposts';


function database_connect(){
    global $h, $d, $u, $p;

    $link = @mysql_connect("$h","$u","$p"); 
    $sql_error = mysql_error();

    if (!$link) { 
        echo "Connection with the database couldn't be made.<br>";
        echo "$sql_error"; 
        exit;
    }

   if (!@mysql_select_db("$d")) {; 
        echo "The database couldn't be selected.";
        exit;
    }
   return $link;
}

if($_SESSION['usrid']){
    database_connect();
    $query = mysql_query("SELECT * FROM craffyusers WHERE id='" .$_SESSION['usrid']. "' ") or die (mysql_error());
    while ($obj = mysql_fetch_object($query)) {
   $id = htmlspecialchars($obj->id);
   $username = htmlspecialchars($obj->username);
   $email = htmlspecialchars($obj->email);
   $realname = htmlspecialchars($obj->name);
   $srvrid = htmlspecialchars($obj->serverid);
   $propic = htmlspecialchars($obj->profilepic);
    };
};

What's the issue here?

because there will 0 or 1 result, you can remove the while clause:

$row2 = mysql_fetch_assoc($result2);

if($row2 && $row2['id']){
 echo "<script type='javascript'>alert('You are already friends with this person.');</script>";
 header('Location: profile.php?id="'.$af.'"');
}else{
    mysql_query("INSERT INTO friends (usr1, usr2)  
            VALUES ('".$id."', '".$af."')") or die(mysql_error());
            echo "<script type='javascript'>alert('You two are friends now!');</script>";
        header('Location: profile.php?id="'.$af.'"');
};

Add this lines at the beginning of the script

        error_reporting(E_ALL);
        ini_set("display_errors", 1);

The error will appear.