thinkPHP实现的省市区三级联动功能示例

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));
      }
    }
  );
}

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;