public function sbjr(){

         $yzc_model=M("Yzc");

         $list = $yzc_model

         ->field("id, mingcheng")

         ->where("shenhe=1")

         ->order("id ASC")

         ->limit($page->firstRow . ',' . $page->listRows)

         ->select();

         $juanshe_model=M("Juanshe");

         $list1 = $juanshe_model

         ->field("id, mingcheng")

         ->where("yzcid=".$list[0]['id'])

         ->order("id ASC")

         ->limit($page->firstRow . ',' . $page->listRows)

         ->select();

         $this->assign('list1', $list1);

         $this->assign('list', $list);

         $this->display();

     }

 <table class="table table-bordered">

     <tr>

         <th>养殖场名称</th>

         <td>

             <select name="yzcmc" id="yzcmc">

                 <foreach name="list" item="vo">

                     <option value="{$vo.id}">{$vo.mingcheng}</option>

                 </foreach>

             </select>

             <span class="form-required">*</span>

         </td>

     </tr>

     <tr>

         <th>栋舍名称</th>

         <td>

             <select name="dsmc" id="dsmc">

                 <foreach name="list1" item="vo">

                     <option value="{$vo.id}">{$vo.mingcheng}</option>

                 </foreach>

             </select>

             <span class="form-required">*</span>

         </td>

     </tr>

 </table>

<script type="text/javascript">

            $('#yzcmc').change(function(){

                var objectModel = {};

                var   value = $(this).val();

                objectModel['id']=value;

                $.ajax({

                    cache:false,

                    type:"POST",

                    url:"{:U('Setting/getjuanshe')}",

                    dataType:"json",

                    data:objectModel,

                    timeout:30000,

                    error:function(){

                        alert("{:U('Setting/getjuanshe')}");

                    },

                    success:function(data){

                        $("#dsmc").empty();

                        var count = data.length;

                        console.log(count);

                        console.log(data);

                        var i = 0;

                        var b="";

                           for(i=0;i<count;i++){

                               b+="<option value='"+data[i].id+"'>"+data[i].mingcheng+"</option>";

                           }

                        $("#dsmc").append(b);

                    }

                });

            });

    </script>

 //获取圈舍 级联菜单

 public function getjuanshe(){

     $id=I('request.id');

     $juanshe_model=M("Juanshe");

     $list = $juanshe_model

     ->field("id, mingcheng")

     ->where("yzcid=".$id)

     ->order("id ASC")

     ->select();

     //$this->ajaxReturn($list,"JSON");

     echo json_encode($list);

 }