Updating drop downs

[suzy_Q]

Hi all,
I'm wanting to update a series of drop down lists depending on what other drop down lists have been chosen.
Here is what i have so far:

<table width="100%" border="0" cellpadding="0" cellspacing="10">
<tr><td colspan="4">
<?
$query_colours = mysql_query("select * from prod_colours,colours WHERE prod_colours.colour_id = colours.colour_id AND prod_colours.prod_id = '$prod_id'"); 
$num_row_colours = mysql_num_rows($query_colours);
 
while ($row_2 = mysql_fetch_array($query_colours)){ 
//the loop will only run while returning results from your mysql query 
?>
<table><tr><td>
<table width="30" height=30 border="1" cellpadding=0 cellspacing=0 bordercolor="#000000" bgcolor="#<? echo $row_2['colour_hex'] ?>">
  <tr><td></td></tr></table></td><td>
        
          <select name="colour_qty_<? echo $prod_id ?>[]">
<?
for ($i = 0; $i < $qty+1; $i++){
?>          
            <option value="<? echo $i ?>"><? echo $i ?></option>
<?
}
?>            
          </select>
          </td></tr></table>
<?
}
?>
        </td>
</tr>
</table>

Ok, lets assume the first series of drop downs (for example colour_qty_1[]) has a $qty value of 10. So the output would look like:

<table width="30" height=30 border="1" cellpadding=0 cellspacing=0 bordercolor="#000000" bgcolor="#000000">
  <tr><td></td></tr></table></td><td>
        
          <select name="colour_qty_1[]">
            <option value="0">0</option>
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
            <option value="5">5</option>
            <option value="6">6</option>
            <option value="7">7</option>
            <option value="8">8</option>
            <option value="9">9</option>
            <option value="10">10</option>
          </select>
		  </td></tr></table>
<table><tr><td>
<table width="30" height=30 border="1" cellpadding=0 cellspacing=0 bordercolor="#000000" bgcolor="#006699">
  <tr><td></td></tr></table></td><td>
        
          <select name="colour_qty_1[]">
            <option value="0">0</option>
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
            <option value="5">5</option>
            <option value="6">6</option>
            <option value="7">7</option>
            <option value="8">8</option>
            <option value="9">9</option>
            <option value="10">10</option>
          </select>

		  </td></tr></table>
<table><tr><td>
<table width="30" height=30 border="1" cellpadding=0 cellspacing=0 bordercolor="#000000" bgcolor="#336633">
  <tr><td></td></tr></table></td><td>
        
          <select name="colour_qty_1[]">
            <option value="0">0</option>
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
            <option value="5">5</option>
            <option value="6">6</option>
            <option value="7">7</option>
            <option value="8">8</option>
            <option value="9">9</option>
            <option value="10">10</option>
          </select>
		  </td></tr></table>

Now, if the user selects any of the drop down lists i want it to update the other lists (in this case the other two) to reflect this change. Therefore if the user selects "7" from the second drop down list the first and third drop down lists should both now contain 3 option values eg:

<select name="colour_qty_1[]">
            <option value="0">0</option>
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
</select>

If there is another way to do this please let me know.
Cheers,
Suzy

[JerryScript]

Use Javascript which treats the drop-down menu as an array, and then you can use pop, push, etc to dynamically alter the other drop-down list's contents.