省份城市菜单联动，AJAX 3级菜单联动

首先看JQ的扩展如下：

//city selected

jQuery.fn.cityselect = function(n,s1,s2,s3) {
if ((n!=3)&&(n!=2)) {n=2};
if (s1=="") {s1="province"};
if (s2=="") {s2="city"};
if (s3=="") {s3="area"};

if (n==2){//二级联动
   //alert(s1+$("select[@name='"+s1+"'] option[@selected]").val());
      $("select[@name='"+s1+"']").bind("change",function(event) {
      $.ajax({
        type: "GET",
        url: "/inc/lib/ajax_city.php",
        data: "n=v2&cityid="+$("select[@name='"+s1+"'] option[@selected]").val(),
        success: function(opt){$("select[@name='"+s2+"']").empty().append(opt);}
       });
     });

}

if (n==3){//三级联动

   $("select[@name='"+s1+"']").bind("change",function(event) {
      $.ajax({
        type: "GET",
        url: "/inc/lib/ajax_city.php",
        data: "n=v2&cityid="+$("select[@name='"+s1+"'] option[@selected]").val(),
        success: function(opt){
        $("select[@name='"+s2+"']").empty().append(opt);
           $.ajax({
          type: "GET",
          url: "/inc/lib/ajax_city.php",
          data: "n=v3&cityid="+$("select[@name='"+s2+"'] option[@selected]").val(),
          success: function(opt){
          $("select[@name='"+s3+"']").empty().append(opt);
          }
         });
        }
       });
     });
    $("select[@name='"+s2+"']").bind("change",function(event) {    
      $.ajax({
      type: "GET",
      url: "/inc/lib/ajax_city.php",
      data: "n=v3&cityid="+$("select[@name='"+s2+"'] option[@selected]").val(),
      success: function(opt){ $("select[@name='"+s3+"']").empty().append(opt);}
     });
  
   });

    }

};

接下来是PHP里的函数如下========

//城市联动脚本
function cityselect($n=2,$s1='province',$s2='city',$s3='area',$v1='320000',$v2='320500',$v3='320501'){
   $db = new DB_Sql;       //初始化数据库
$db->connect(DB_Database, DB_Host, DB_User, DB_Password); //数据库连接
$db->DB_Sql("set names gbk");
//联动AJAX脚本
$tmp = "<script type=\"text/javascript\"> \n";
$tmp .= '$(document).ready(';
$tmp .= "function(){ \n";
$tmp .= '$().cityselect('.$n.',\''.$s1.'\',\''.$s2.'\',\''.$s3.'\');';
$tmp .= "\n";
$tmp .= "});\n";
$tmp .= "</script>\n";
//省份选择
$tmp .= "<select id=\"".$s1."\" name=\"".$s1."\" >\n";
$db->query("select * from sz_chinacity where right(CityPostCode, 4) = '0000' order by CityID asc");
   while ($db->next_record()){
    if ($db->Record['CityPostCode']==$v1){
     $tmp .= "<option value=\"".$db->Record['CityPostCode']."\" selected>".$db->Record['CityName']."</option>\n";
    }else{
     $tmp .= "<option value=\"".$db->Record['CityPostCode']."\">".$db->Record['CityName']."</option>\n";
    }
   }
$tmp .= "</select>\n";
//城市选择
$tmp .= "<select id=\"".$s2."\" name=\"".$s2."\">\n";
$cityid = substr($v1,0,2);
$db->query("select * from sz_chinacity where Right(CityPostCode, 2) = '00' and Left(CityPostCode, 2)='".$cityid."' and Right(CityPostCode, 4) <> '0000' order by CityID asc");
   while ($db->next_record()){
    if ($db->Record['CityPostCode']==$v2){
     $tmp .= "<option value=\"".$db->Record['CityPostCode']."\" selected>".$db->Record['CityName']."</option>\n";
    }else{
     $tmp .= "<option value=\"".$db->Record['CityPostCode']."\">".$db->Record['CityName']."</option>\n";
    }
   }
$tmp .= "</select>\n";


if ($n==3){
//地区选择
$tmp .= "<select id=\"".$s3."\" name=\"".$s3."\">\n";
$cityid = substr($v2,0,4);
$db->query("select * from sz_chinacity where Left(CityPostCode, 4)='".$cityid."' and Right(CityPostCode, 2) <> '00' order by CityID asc");
   while ($db->next_record()){
    if ($db->Record['CityPostCode']==$v3){
     $tmp .= "<option value=\"".$db->Record['CityPostCode']."\" selected>".$db->Record['CityName']."</option>\n";
    }else{
     $tmp .= "<option value=\"".$db->Record['CityPostCode']."\">".$db->Record['CityName']."</option>\n";
    }
   }
$tmp .= "</select>\n";
}
echo $tmp;
}

调用的时候：<?php cityselect(2); ?>