como hago un Select dependiente de BD

[gildus]

Holas,

Capaz te sirva esto, lo modifique un poquito:

Código PHP:

<?php
include ("conexion.php");
?>
<form id="form1" name="form1" method="post">
<div id=dependiente>
 
<!--Combo principal-->
<select name="regimen" onChange="redirect(this.options.selectedIndex)" style='width:160'>
<option value=0>Regimen</option>
<?
$res = mysql_query("SELECT id_regimen, regimen FROM regimenes ORDER BY regimen");
while($rw = mysql_fetch_array($res))
    echo "<option value='".$rw['id_regimen']."' ";
    if(isset($_POST['regimen']) && !empty($_POST['regimen']) && ($_POST['regimen']== $rw['id_regimen']) )
        echo 'selected';
    echo ">";
    echo    $rw['regimen'];
    echo "</option>";
?>
</select>
 
<!--Combo dinámico-->
<select name="afiliadora" style='width:200px'>
<option value=0>Afiliadoras</option>
<?
if(isset($_POST['id_regimen']) && !empty($_POST['id_regimen']))
{   $res = mysql_query("SELECT id_afiliadora, id_regimen, afiliadora FROM afiliadoras WHERE id_regimen='".$_POST['id_regimen']."' ORDER BY afiliadora");
    while($rw = mysql_fetch_array($res))
        echo "<option value='".$rw['id_afiliadora']."' >";      
        echo    $rw['afiliadora'];
        echo "</option>";
}
 
?>
</select>
</div>
</form>
 

Saludos
Gildus