<button type="submit" name="hocsinh" class="btn btn-primary">Thêm HS</button> </form> </div> </div> <br><br><br> <div class="row"> <div class="col-sm-4"> <select onchange="ajaxGetLop(this.value);" class="form-control"> <option>-----------</option> <?php $db = new Database(); $arrData = $db->getAlldata('giao_vien'); foreach ($arrData as $key => $value) { echo '<option value="' . $value['id'] . '">' . $value['ten'] . '</option>'; } ?> </select> </div> <div class="col-sm-4"> <select id='ajaxLop' onchange="ajaxGetHocSinh(this.value);" class="form-control"> <option>-----------</option> </select> </div> <div class="col-sm-4"> <select id='ajaxHocSinh' class="form-control"> <option>-----------</option>