$db = M("order");
$db->transStart();
try {
    $id = $db->insert(array("order_no" => "KQ001", "amount" => 100));
    $db->table("order_item")->insert(array("order_id" => $id, "goods_id" => 1));
    $db->commit();
} catch (\Exception $e) {
    $db->rollback();
    return $this->jsonReturn(0, "下单失败：" . $e->getMessage());
}