CI框架中事务封装的很完善，使用起来很简单
1.不开启事务
//不开启事务 前两个sql 能够执行成功,第三个执行失败
$this->device_model->addForCamera(1, '爱三123', '2016122903', 0);
$this->device_model->setStateInDevices(1, array(2));
$this->device_model->addForCamera(1, '爱三1234567890', '2016122903', 0);
2.自动事务
//失败自动回滚
$this->db->trans_start();
//三条sql 都执行失败
$this->device_model->addForCamera(1, '爱三123', '2016122903', 0);
$this->device_model->setStateInDevices(1, array(2));
$this->device_model->addForCamera(1, '爱三1234567890', '2016122903', 0); $this->db->trans_complete();
3.手动事务
//若失败手动回滚 成功手动提交
$this->db->trans_begin(); //三条sql 都执行失败
$this->device_model->addForCamera(1, '爱三123', '2016122903', 0);
$this->device_model->setStateInDevices(1, array(2));
$this->device_model->addForCamera(1, '爱三1234567890', '2016122903', 0); if ($this->db->trans_status() === false) {
$this->db->trans_rollback();
} else {
$this->db->trans_commit();
}