在php中提交表单后保持url相同

Question

I have this simple form that updates the values in database, the url of the page is

www.example.com?id=1

After i submit the form the values get updated and i get a success message but the url gets changed, it becomes

www.example.com

Can anyone tell how i can keep the url same i.e: www.example.com?id=1

The code is as follows

<?
if ($_SERVER["REQUEST_METHOD"] == "POST") 
    {
        $text = mysqli_real_escape_string($con, $_POST['textvalue']);
        $title = mysqli_real_escape_string($con, $_POST['title']);
        $blogid = mysqli_real_escape_string($con, $_POST['blogid']);

        $sql = "UPDATE blog SET text='".$text."', title='".$title."'  WHERE id='".$blogid."'";
        if (mysqli_query($con, $sql)) 
            {
                $msg = "Blog updated";
            } 
        else 
            {
                echo "There was an error";
            }
    }
?>

<div>
    <?
        if($msg!="")
            {
                echo $msg;
            }
    ?>  
    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>" method="post" enctype="multipart/form-data" >

        <input type="text" name="title"  value="<? echo $title; ?>" style="width:100%;"/>
        <textarea name="textvalue" ><? echo $text; ?></textarea>
        <input type="hidden" name="blogid"  value="<? echo $blogid; ?>"/>
        <input type="submit" name="edit" alt="edit" value="Edit"/>
    </form>
</div>