problemino con select dinamica

[Lino80]

CREATE TABLE `regioni` (
  `id` int(11) unsigned NOT NULL, 
  `regione` text NOT NULL, 
  PRIMARY KEY (`id`)
);

CREATE TABLE `province` (
  `id` int(10) unsigned NOT NULL,
  `id_regione` int(10) unsigned NOT NULL, 
  `provincia` text NOT NULL,
  `sigla` varchar(2) NOT NULL,
  PRIMARY KEY (`id`)
);

CREATE TABLE IF NOT EXISTS `comuni` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
  `id_regione` int(10) unsigned NOT NULL, 
  `id_provincia` int(10) unsigned NOT NULL, 
  `comune` text NOT NULL, 
  PRIMARY KEY (`id`)
);