add to cart

<?php session_start();
include "config.php";

$id = $_GET['id'];

$cari_barang = "SELECT * FROM barangtbl WHERE id=$id";
$hasil_barang = mysql_query($cari_barang);
$data_barang = mysql_fetch_array($hasil_barang);

$ciri = $data_barang['id'];
$nam = $data_barang['judul_barang'];
$berat = $data_barang['berat'];
$jumlah_berat = $data_barang['jumlah_berat'];
$har = $data_barang['harga'];
	if((isset($_SESSION['userlogin'])) =='')
	{
		header("location:fail_buy.php");
	}
	else
	{
		$member = $_SESSION['userlogin'];
		if($hasil_barang)
		{
			require ("faktur.php");
			$cari_transaksi = "SELECT * FROM transaksirincitbl WHERE username='".$member."' AND id = '".$id."' AND notransaksi ='".$faktur."'";
			$hasil_transaksi = mysql_query($cari_transaksi);
			$temukan = mysql_num_rows($hasil_transaksi);
			$data_transaksi = mysql_fetch_array($hasil_transaksi);
			if($temukan==0)
			{
				$query = "INSERT into transaksirincitbl (notransaksi,username,id,nama,berat,jumlah_berat,harga,jumlah,subtotal)
									VALUES ('$faktur','$member','$ciri','$nam','$berat','$berat','$har','1.0','$har')";
				$result = mysql_query($query);

				header("location:shopping_cart.php");
			}
				else
				{
					$jmllama = $data_transaksi['jumlah'];
					$jmltambah = $jmllama + 1;
					$subtotaltambah = $jmltambah * $har;

					$jmlberatlama = $data_transaksi['berat'];
					$jmlberattambah = $jmlberatlama * $data_transaksi['jumlah_berat'];

					$query = "UPDATE transaksirincitbl SET jumlah = '".$jmltambah."',jumlah_berat = '".$jmlberattambah."',subtotal = '".$subtotaltambah."'
										WHERE notransaksi ='".$faktur."' and id ='".$id."'";
					$result = mysql_query($query);
					header("location:shopping_cart.php");
				}
		}
			else
			{
				echo "Data gagal diInput..!";
			}
	}
?>