1.html

  <select class="form-control" name="category" id="category">
      <option value="0">一級分類</option>
     {foreach $list as $vo} 
      <option value="{$vo.id}">{$vo.name}</option>
     {/foreach}
   </select>

     <select class="form-control" name="secondcategory"
 
 id="secondcategory">
      <option value="0">二級分類</option>
     </select>

2.jq

/*分類*/
$("#category").change(function(){

  a=$(this).val();
  if(a !=0){
        $.ajax({     
       type: "POST",     
       dataType: "json",     
       url: "{:url('stat/getcategory')}",     
       data: "parentid="
 
+a,  
       success: function (data) {   
           $("#secondcategory").html("<option value=''>請選擇二級分類</option>");

          $.each(data, function(i, item) {
                            $("#secondcategory").append("<option value='" + item.id + "'>" + item.name + "</option>"
 
);

                        });

       },     
       eror: function (data) {   
          alert("請求超時!")    
       }     
    }); 
  }


});

3.thinkphp

   /*商品分類統計*/
    public function goodscategory()
    {
        /*一級分類*/
        $map = array('uniacid' => 6, 'parentid' => 0, 'level' => 1);
        $field = "id,name";
        $list = db('ims_ewei_shop_category')->where($map)->field($field)->select();
        $this->assign('list', $list);
        return $this->fetch();
    }
    /*獲取二級分類*/
    public function getcategory()
    {
        $parentid = intval(input('post.parentid'));
        $map = array('uniacid' => 6, 'parentid' => $parentid, 'level' => 2);
        $field = "id,name";
        $categorylist = db('ims_ewei_shop_category')->where($map)->field($field)->select();
        exit(json_encode($categorylist));
    }

“`