三级联动菜单

html

<p>
                  <label>区域</label>
                <select name="province" id="province" onchange="region('province','city','1')">
                    <option value="">省份</option>
                    {$region_province}
                </select>
                <select name="city" id="city" onchange="region('city','district','2')">
                     <option value="">地级市</option>
                    
                </select>
                <select name="district" id="district">
                     <option value="">市、县级市</option>
                  
                </select>
                
              </p>

js

<script type="text/javascript">
              function region(t,p,type){ 
                var a =document.getElementById(t).value;                  
                  $.ajax({
                        url: "index.php?action=ajax_region&parent_id="+a+"&retion_type="+type,
                        success: function(html){
                            html += "<option value=''>请选择</option>";
                            $("#"+p).html(html)
                        }
                  });
              }
              </script>

ajax，php代码

function region($parent_id,$region_type){           //region(0,北京市)
    $where = "where parent_id = $parent_id";
    
    $sql = mysql_query("select * from rv_region $where");
    //echo $where;
    while($re = mysql_fetch_row($sql)){
        $arr[] = $re;    
    }
    if($region_type =='1'){
        $province .= "<option value=''>地级市</option>";
    }else if($region_type =='2'){
        $province .= "<option value=''>市、县级市</option>";    
    }
    
    foreach($arr as $k=>$val){
        $province .= "<option value='".$val[0]."'>".$val[2]."</option>";
        
    }
    
    return $province;
}   

$parent_id = $_GET['parent_id'];
$region_type = $_GET['retion_type'];
    
echo region($parent_id,$region_type);

三级联动mysql数据