Disable updating data when database is empty - php

Question

I am having a problem when I want to echo "The stock is less than what you want". The problem is the user still can update the cart when the stock in my database less that what the user wants. It should show an error "The stock is less than what you want".
This is my code.
<?php session_start();
require("config.php");
$user = $_SESSION['userlogin'];
$cek = mysql_query("SELECT * FROM transaksitbl WHERE username = '$user' AND status ='0'") or die(mysql_error());
$result = mysql_num_rows($cek);
$data = mysql_fetch_array($cek);
if ($result > 0)
{
$faktur =$data['notransaksi'];
for ($i=1; $i<=$_POST['n']; $i++)
{
$idp = $_POST['id'.$i];
$cari2 = mysql_query("SELECT * FROM barangtbl WHERE id='$idp'") or die(mysql_error());
$row2 = mysql_fetch_array($cari2);
$har = $row2['harga'];
$stock = $row2['stock'];
if($_POST['n'] <= $row2['stock'])
{
echo "The stock is less than what you want";
}
if ($cari2)
{
$jmlubah = $_POST['jumlah'.$i];
$beratnew = $jmlubah*$row2['berat'];
$totubah = $jmlubah*$har;
$query = mysql_query("UPDATE transaksirincitbl SET jumlah = $jmlubah, jumlah_berat = $beratnew, total_berat = $beratnew, subtotal=$totubah
WHERE id ='$idp' and username = '$user' And notransaksi =$faktur") or die(mysql_error());
}
}
}
header ("location:shopping_cart.php");
?>

Answer 1

If i understood you properly the
if($cari2){}
function is executing?
All you are checking there is if the $cari2 variable is true.
Simply make a else statement out of the if($cari2){} statement so that if the stock is less than you wan't the second if statement won't get executed.
So, like this:
if($_POST['n'] <= $row2['stock']){
echo "The stock is less than you want";
}
else {
if($scari2){
$jmlubah = $_POST['jumlah'.$i];
$beratnew = $jmlubah*$row2['berat'];
$totubah = $jmlubah*$har;
$query = mysql_query("UPDATE transaksirincitbl SET jumlah = $jmlubah, jumlah_berat = $beratnew, total_berat = $beratnew, subtotal=$totubah
WHERE id ='$idp' and username = '$user' And notransaksi =$faktur") or die(mysql_error());
} else {
die('Woop, there seems to be a problem with the $scari2 variable. The value is:' . $scari2);
} // END OF INNER ELSE
} // END OF ELSE
And one more thing NEVER forget to use the mysql_real_escape_string() function on a variable before submiting it's value to the database.