[Update multiple row at once]

hello  all

i am building a shopping system, but i am stuck. i want to update items in the database but it is affecting only the last row.
thanks for the help

			
			<input type="hidden" class="form-control" name="prod_id"  value="'.$values["product_ids"].'" />
			<td><input type="text" class="form-control" readonly name="prod_name"  value="'.$values["product_name"].'" /></td>
			<td><input type="text" class="form-control" readonly name="prod_type"  value="'.$values["product_type"].'" /></td>
			<td><input type="text" class="form-control" readonly name="prod_size"  value="'.$values["product_size"].'" /></td>
			<td><input type="text" class="form-control" readonly name="prod_qty"  value="'.$values["product_quantity"].'" /></td>
			<td><input type="text" class="form-control" readonly name="prod_price"  value="'.$values["product_price"].'" /></td>
			<td><input type="text" class="form-control" readonly name="total_price"  value="'.number_format($values["product_quantity"] * $values["product_price"], 2).'" /></td>


if(isset($_POST['enter']))
{

require_once 'database_connection.php';

	$prod_name 		= $_POST['prod_name'];
	$prod_id  		= $_POST['prod_id'];
	$prod_type  	= $_POST['prod_type'];
	$prod_size  	= $_POST['prod_size'];
	$prod_qty 	 	= $_POST['prod_qty'];
	$prod_price  	= $_POST['prod_price'];
	$total_price  	= $_POST['total_price'];
	$trans_ref 		= mt_rand(10000, 99999);


$sql = "INSERT INTO test_sales (
trans_ref, 
prod_id, 
prod_name,
prod_type,
prod_size,
prod_qty,
prod_price,
total_price,
trans_date
) 
VALUES (
:trans_ref, 
:prod_id, 
:prod_name,
:prod_type,
:prod_size,
:prod_qty,
:prod_price,
:total_price, 
NOW()
)";
$stmt = $connect->prepare($sql);
$stmt->execute(array(
':trans_ref'	=> $trans_ref,
':prod_id' 		=> $prod_id,
':prod_name' 	=> $prod_name,
':prod_type' 	=> $prod_type,
':prod_size' 	=> $prod_size,
':prod_qty'		=> $prod_qty,
':prod_price' 	=> $prod_price,
':total_price' 	=> $total_price
));

$num_rows = $stmt->rowCount();

if($num_rows){

 
    $sql = "
	UPDATE  products
	SET 	qty 		= qty - '$prod_qty'
	WHERE 	prod_name 	= '$prod_name'
	AND 	prod_id 	= '$prod_id'
	";
	$stmt = $connect->prepare($sql);
	//$stmt->bindValue(':qty', $prod_qty, PDO::PARAM_STR);
	$stmt->bindValue(':prod_name', $prod_name, PDO::PARAM_STR);
	$stmt->bindValue(':prod_id', $prod_id, PDO::PARAM_STR);
	$stmt->execute();




echo  '<div class="alert bg-success text-center">ITEMS ADDED</div>';
unset($_SESSION["shopping_cart"]);


}else{
	
	echo '<div class="alert bg-danger text-center">A PROBLEM OCCURRED</div>';

}

}