Thinkphp实现省市区三级联动

一张表实现省市区三级联动【3409条数据】
    public function index(){
        $province = M('Tree')->where ( array('pid'=>1) )->select ();
        $this->assign('province',$province);
        $this->display();
    
    }
    public function getRegion(){
        $Region=M("Tree");
        $map['pid']=$_REQUEST["pid"];
        $map['type']=$_REQUEST["type"];
        $list=$Region->where($map)->select();
        echo json_encode($list);
    }
     <select name="province" id="province" onchange="loadRegion('province',2,'city','{:U('Index/getRegion')}');">
        <option value="0" selected>省份/直辖市</option><volist name="province" id="vo"> 
        <option value="{$vo.id}" >{$vo.name}</option></volist>
     </select>          
     <select name="city" id="city"  onchange="loadRegion('city',3,'town','{:U('Index/getRegion')}');">
       <option value="0">市/县</option>
     </select>
	 <select name="town" id="town">
       <option value="0">镇/区</option>
     </select>
function loadRegion(sel,type_id,selName,url){
	jQuery("#"+selName+" option").each(function(){
		jQuery(this).remove();
	});
	jQuery("<option value=0>请选择</option>").appendTo(jQuery("#"+selName));
	if(jQuery("#"+sel).val()==0){
		return;
	}
	jQuery.getJSON(url,{pid:jQuery("#"+sel).val(),type:type_id},
		function(data){
			if(data){
				jQuery.each(data,function(idx,item){
					jQuery("<option value="+item.id+">"+item.name+"</option>").appendTo(jQuery("#"+selName));
				});
			}else{
				jQuery("<option value='0'>请选择</option>").appendTo(jQuery("#"+selName));
			}
		}
	);
}
</script>
DROP TABLE IF EXISTS `tp_tree`;
CREATE TABLE `tp_tree` (
  `id` int(5) unsigned NOT NULL AUTO_INCREMENT,
  `pid` int(5) unsigned NOT NULL DEFAULT '0',
  `name` varchar(120) DEFAULT NULL,
  `type` tinyint(1) DEFAULT '2',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=3410 DEFAULT CHARSET=utf8;

代码技巧