更新后product_sku和product_image尚未更新...但是其他值也已更新...if (isset($_POST['update_product'])) {        $product_id           =$_POST['product_id'];        $product_name         =$_POST['proname'];        $product_sku          =$_POST['prosku'];        $product_price        =$_POST['proprice'];        $product_height       =$_POST['proheight'];        $product_width        =$_POST['prowidth'];        $product_weight       =$_POST['proweight'];        $product_category     =$_POST['procategory'];        $product_description  =$_POST['prodesc'];        $product_image        =$_POST['product_image'];            $sql = "UPDATE  product ". " SET product_name='$product_name', product_price='$product_price',product_sku='product_sku',product_height='$product_height', product_width='$product_width',product_weight='$product_weight',product_category='$product_category',product_image='$product_image', product_description='$product_description' "."WHERE product_id=$product_id";    $result=mysqli_query($conn,$sql);         if(! $result ) {               die('Could not update data: ');            }            echo "Updated data successfully\n";            mysqli_close($conn);        }