lo puse de este modo:
Código HTML:
<script type="text/javascript" src="scripts/jquery-1.5.1.min.js"></script>
<script language="JavaScript" type="text/JavaScript">
$(document).ready(function(){
$('select[name="categoria"]').change(function(){
var id_categoria = $(this).val();
$('select.subcategoria').hide();
$('select[name="subcategoria-'+id_categoria+'"]').show();
});
});
</script>
Código PHP:
<select name="<?php echo $campo ?>">
<option value="0">-</option>
<?php
$conn = DataBase::getInstance();
$rel=false;
$relacion='_'.$campo;
$conn->setQuery('SELECT * FROM `_'.$campo.'` ORDER BY id ASC');
if ($conn->len()==0){
$rel=true;
$relacion=$campo;
$conn->setQuery('SELECT * FROM `'.$campo.'` ORDER BY id ASC');
}
if ($conn->len()==0){
$rel=true;
$relacion=$campo.'s';
$conn->setQuery('SELECT * FROM `'.$campo.'s` ORDER BY id ASC');
}
if ($conn->len()>0){
$rs = $conn->loadObjectList();
foreach($rs as $valor){?>
<option value="<?php echo $valor->id ?>"><?php echo $valor->titulo ?></option>
<?php
}}?>
</select>
pero el combo de subcategoria no reconoce el id de categoria correspondiente.