Problem mit UPDATE by ID, meldung erfolgreich ausgeführt aber dbinhalt wird nicht geändert!

<?php
	require("settings.php");  
	if(isset($_POST["id"]) && isset($_POST["title"]) && isset($_POST["text"])){  
		// Create connection
		$conn = new mysqli($servername, $username, $password, $dbname);
		// Check connection
		if ($conn->connect_error) {
			die("Connection failed: " . $conn->connect_error);  
		}
        $tempid = addslashes($_POST["id"]);		  
		$temptitle = addslashes($_POST["title"]);  
		$temptext = addslashes($_POST["text"]);  
		
		$sqlupdate = "UPDATE news SET title=$temptitle, text=$temptext WHERE id=$tempid";  

$update = mysql_query($sqlupdate);
if ($sqlupdate == TRUE){
	echo "News bearbeitet!";  
		} else {
			echo "Error: " . $sqlupdate . "<br>" . $conn->error;  
		}

		$conn->close();
	}
	else{
		echo "Keine Daten gesetzt.";  
} 
?>

private void edit_news_save_Click(object sender, EventArgs e)
        {
            var request = (HttpWebRequest)WebRequest.Create("meine.adresse"); //das meine adresse habe ich nachträglich geändert!  
            var postData = "id=" + edit_news_id.Text;    // txtnewNewsTitle  
                postData += "&title=" + edit_news_title.Text;  
                postData += "&text=" + edit_news_text.Text;  

            var data = Encoding.ASCII.GetBytes(postData);

            request.Method = "POST";  
            request.ContentType = "application/x-www-form-urlencoded";  
            request.ContentLength = data.Length;

            using (var stream = request.GetRequestStream())
            {
                stream.Write(data, 0, data.Length);
            }

            var response = (HttpWebResponse)request.GetResponse();

            var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
            // lblStatus.Text = responseString;
            MessageBox.Show(responseString);