SQL UPDATE无法正常工作

I am trying to update some of the data in a database called customer. This is my code

<?php

Require("dbconnect.php");

$Customer_id = $_POST['Customer_id'];
 $Customer_title = $_POST['Customer_title'];
 $Customer_forename = $_POST['Customer_forename'];
 $Customer_surname = $_POST['Customer_surname'];
 $Customer_contact = $_POST['Customer_contact'];

    ?>

all the variables are holding the correct data as I have test echoed them. No errors are recieved when I run this code however it is not updating the database either? Can anyone help? Thank in advance!

There is one little thing that will quite possibly fix your problem. It is in the quotation.

$sql = "UPDATE `a6123854_a220559`.`Customer`
SET Customer_forename='".$Customer_forename."',
Customer_surname='".$Customer_surname."'
WHERE Customer_id='".$Customer_id."'";

String constants need single quotes (forename and surname):

$sql = "UPDATE `a6123854_a220559`.`Customer` 
SET Customer_forename = '".$Customer_forename."', Customer_surname = '".$Customer_surname."'
WHERE Customer_id = ".$Customer_id."";

Please note that your code may be susceptible to SQL injection.