Website Rename PHP

<?php

session_start();
if( $_SESSION["username"]==""){
 header("Location: http://filewallet.site88.net/");
}
else{
       $servername = "mysql1.000webhost.com";
       $username = "a9691255_naveed";
       $password = "abmirzass123";
       $dbname = "a9691255_webiste";
$userid=$_SESSION["username"];

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
if(isset($_GET["choice"])){
         $choice=$_GET["choice"];
if($choice==1)
{
      $path=$_GET["path"];
      $filename=$_GET["filename"];
}
if($choice==2)
{

      $filename=$_GET["filename"];
echo $filename;
}
}

}

?>
<html>
<body>
<?php
if(isset($_POST["submit"])){
         $oldname=$_POST["oldname"];
         $newname=$_POST["newname"];
         $filepath="upload/".$userid;
if (strpos($oldname, '.') !== false) {
    $filecheck=1;
}
else{$filecheck=2;}
if($filecheck==1){
      $query="update fileuploads set filename='".$newname."' ,filepath='".$filepath."/".$newname."' where filename='".$oldname."' and userid='".$userid."'";
                if($conn->query($query))
                        {
                            if(rename($filepath."/".$oldname,$filepath."/".$newname))
                            header("Location: main.php?renamecheck=1");
                                                        else
                                                         header("Location: main.php?renamecheck=2");
}
    }
if($filecheck==2){
if(rename($filepath."/".$oldname,$filepath."/".$newname))
                            header("Location: main.php?renamecheck=1");
}

}

?>
<form method="post" action="rename.php">
Old File Name : <input type="text" name="oldname" width="100px" value="<?php echo $filename; ?>" readonly><br>
New File name : <input type="text" name="newname" width="100px"><br>
<input type="submit" name="submit">
</form>
</body>
</html>