Need help with Storage system

[Fearreaper]

I'm busy with a small storage system for my site, but i encounter some problems with it.

I have successfully managed to get all products from the order, and traced on what spots those product are in the warehouse.

It looks like this atm http://img37.imageshack.us/img37/7302/tableordereng.jpg

 

this is the code i have atm (sorry i program in dutch, i hope its abit understandable)

 

<?php

$query = "select * from `orderregel` WHERE `ordernr`='".$ordernr."'";
   $row = mysql_fetch_array( $query );
            
   echo "<table border=1 width=680 bgcolor=#FFFFFF>
     <tr>
            <th width= 100>artikelnummer</th>
        <th width= 100>productnaam</th>
            <th width= 40>Plaats</th>
        <th width= 40>aantal in magazijn</th>
            <th width= 40>aantal nodig</th>          
     </tr>
         </table>";  
                      
            foreach ( self::find_by_sql($query) as $user)
            {   
                $query2 = "select * from magazijn WHERE artikelnr = ".$user->artikelnr."";
                $row = mysql_fetch_array( $query );
            
                foreach ( self::find_by_sql($query2) as $magazijn)
                {
                echo "<table class= order_overzicht border= 0 width= 680>";
                echo "<tr>    
                        <td width= 100>".$magazijn->artikelnr."</td>            
                        <td width= 100>".$magazijn->productnaam."</td>
                        <td width= 40>".$magazijn->magazijn_plaats."</td>
                        <td width= 40>".$magazijn->aantal."</td>
                        <td width= 40>".$user->aantal."</td>
                      </tr>
                      </table>";
                }
            }
?>

 

The problem i have now is, that i want it to do the following.

for example someone orders 430 packages of Haribo Kers Cola (see imageshack upload). I first want it to empty spot 16 in the wherehouse.

Only when spot 16 is empty, i want it to go to the next spot (19) wich contains the same product.

 

the end result would be something like this:

 

http://img690.imageshack.us/img690/6246/tableorderneweng.jpg

 

i hope you guys can help me out on this one, becouse i have no clue how i can resolve this problem

 

thx in advance

 

(Sorry btw for my bad english )