Add a specific quantity into shoppingcart
<p>I have a table where It shows the product I have choosen in the database....  In this table I have an <code>&lt;input type=\"text\" name=\"introduce[]\"&gt;&lt;/td&gt;";</code>  </p>

<pre><code> while($producto= $db-&gt;next()) {

        echo "&lt;form id=\"form\" name=\"formu\"  action =\"shoppingcart.php?action=add&amp;id=".$producto['id_producto']."\" method=\"POST\" target=\"_blank\"&gt;";
        echo "&lt;tr&gt;";
        echo "&lt;td style='font-size:20px' align='center'&gt;&lt;input type='submit' value='PEDIR'&gt;&lt;/td&gt;";  
        echo "&lt;td style='font-size:20px' align='center'&gt;&lt;input type=\"text\" name=\"introduce[]\"&gt;&lt;/td&gt;";
        echo "&lt;td style='font-size:20px' align='center'&gt;".$producto['codinterno']."&lt;/td&gt;";
        echo "&lt;td style='font-size:20px' align='center'&gt;".$producto['nombreproducto']."&lt;/td&gt;";
        echo "&lt;td style='font-size:20px' align='center'&gt;".$producto['nombrecompañia']."&lt;/td&gt;";
        echo "&lt;td style='font-size:20px' align='center'&gt;".$producto['cantidad']."&lt;/td&gt;";
        echo "&lt;td style='font-size:20px' align='center'&gt;".$producto['codbarras']."&lt;/td&gt;";
        echo "&lt;/tr&gt;";
}
</code></pre>

<p>In this input I would like to put manually a quantity (a number). This quantity is POSTED to another page call shoppingcart.php where I have the following switch option.</p>

<blockquote>
<pre><code>  &lt;?php
  switch($action) { 
  case "add":
$_SESSION['cart'][$product_id]= ???????????????; 
break; } ?&gt;
</code></pre>
</blockquote>

<p>Finally, I would like that quantity that I have introduced manually in the table to the quantity of the product in the shopping cart</p>
