Have a form on your webpage that when you enter in a 12 digit number and press search it use's the database to get just that number and tell you the following information:
Well you do a SELECT on the data from the form and then you can use mysql_num_rows() to see how many results there were. You use this info in an if statement to determine what information you show.
$sql = "SELECT name, price FROM table WHERE barcode = '{$_POSTї'barcode']}'";
@$result = mysql_query($sql) or die(mysql_error().'<p>'.$sql.'</p>');
if (mysql_num_rows($result) > 0) {
$row = mysql_fetch_assoc($result);
echo 'Product Name: '.$rowї'name'];
echo '<br />';
echo 'Product Barcode No.: '.$_POSTї'barcode'];
echo '<br />';
echo 'Product Price: '.$rowї'price'];
} else {
echo 'Sorry, But this product hasnt been put into the database';
}
Obviously I know nothing about the names of the relevant fields in your database so you'll have to change that, I also don't know what you've called the field on your form or what version of PHP you are running.