<label>層次</label><select name="level" id="level"> <option value="1">本科</option> <option value="2">高職（專科）</option></select><label>專業</label><select name="major" id="major"> <option value="">--</option></select>

$("#level").click(function(){      $.ajax({       type:"POST",       url:"{:U('Target/queryMajor')}",       dataType: "json",       data:{        level:$('#level').val()       },       success:function(data){        $("#major").empty();        switch (data.status){         case '1':          $("#major").append("<option value='' >--</option>");          $.each(data.data,function(index,val){           $("#major").append('<option value='+val.major+' >'+val.major+'</option>');          });          break;         case '0':          $("#major").append("<option value='' >--</option>");          break;        }        return false;       }      });      return false;     });

public function queryMajor() { if(I('post.level') == 1){$ccmc = '本科';}else{$ccmc = '高職（專科）';} $dao = M('Plan'); $condition["ccmc"] = $ccmc; $record = $dao->where($condition)->field('major')->select(); if($record != null){ $this->ajaxReturn($record,'','1'); }else{ $this->ajaxReturn('','','0'); } }