Renaming Uploaded Photo

[phpNOvice]

Hello killers,

I have manage to create codes that could upload a image that is purposely to serve as profile picture of a certain student. My problem is how to rename it to aN AUTO COLLATE UNIQUE ID NUMBER so that i can display it specifically to a certain student account which bears the unique id number. The variable is $student_id.

<?php
    session_start();
    $session_id = $_SESSION['user_id'];
    if($session_id == null){
       header("location:Student_Edit.php");
       die();
    }
    include 'Connect.php';
    $flag = "";
    $result = mysql_query("SELECT * FROM student_information where student_id='{$_SESSION['user_id']}'",$link_id);;
    $data = mysql_fetch_array($result);
?>     
<div class="style3" >
    <?php
    $uploadpath = 'upload/';     
    $max_size = 2000;         
    $alwidth = 900;           
    $alheight = 800;          
    $allowtype = array('bmp', 'gif', 'jpg', 'jpe', 'png','psd');       
    if(isset($_FILES['fileup']) && strlen($_FILES['fileup']['name']) > 1) {
    $uploadpath = $uploadpath . basename( $_FILES['fileup']['name']);      
    $sepext = explode('.', strtolower($_FILES['fileup']['name']));
    $type = end($sepext);      
    list($width, $height) = getimagesize($_FILES['fileup']['tmp_name']);     
    $err = '';         
    if(!in_array($type, $allowtype)) $err .= 'The file: <b>'. $_FILES['fileup']['name']. '</b> not has the allowed extension type.';
    if($_FILES['fileup']['size'] > $max_size*1000) $err .= '<br/>Maximum file size must be: '. $max_size. ' KB.';
    if(isset($width) && isset($height) && ($width >= $alwidth || $height >= $alheight)) $err .= '<br/>The maximum Width x Height must be: '. $alwidth. ' x '. $alheight;
    if($err == '') {
    if(move_uploaded_file($_FILES['fileup']['tmp_name'], $uploadpath)) { 
      echo 'File: <b>'. basename( $_FILES['fileup']['name']). '</b> successfully uploaded:';
      echo '<br/>File type: <b>'. $_FILES['fileup']['type'] .'</b>';
      echo '<br />Size: <b>'. number_format($_FILES['fileup']['size']/1024, 3, '.', '') .'</b> KB';
      if(isset($width) && isset($height)) echo '<br/>Image Width x Height: '. $width. ' x '. $height;
      echo '<br/><br/>Image address: <b>http://'.$_SERVER['HTTP_HOST'].rtrim(dirname($_SERVER['REQUEST_URI']), '\\/').'/'.$uploadpath.'</b>';
    }
    else echo '<b>Unable to upload the file.</b>';
  }
  else echo $err;
}
?>

Please modify my codes to rename the uploaded file to the student id of the student who is uploading it.

[phpNOvice]

this has been solved