php7.0与CI

Lewis-liu

php7.0和CI配置差不多了，第一次都可以运行项目了。但是隔了一个晚上，第二天又报同样的错误，这该怎么解决啊，求大神指教。
Fatal error: Uncaught Error: Call to a member function fetchAll() on boolean in F:\phpStudy\phpStudy1\WWW\my_project\supervisit\system\database\drivers\pdo\pdo_result.php:41 Stack trace: #0 F:\phpStudy\phpStudy1\WWW\my_project\supervisit\system\database\DB_driver.php(386): CI_DB_pdo_result->num_rows() #1 F:\phpStudy\phpStudy1\WWW\my_project\supervisit\application\models\customer_order.php(240): CI_DB_driver->query('select customer...') #2 F:\phpStudy\phpStudy1\WWW\my_project\supervisit\application\controllers\h5_app\interface_supervisit.php(1564): Customer_order->get_task_list(false) #3 F:\phpStudy\phpStudy1\WWW\my_project\supervisit\system\core\CodeIgniter.php(359): Interface_supervisit->user_task_list() #4 F:\phpStudy\phpStudy1\WWW\my_project\supervisit\index.php(202): require_once('F:\\phpStudy\\php...') #5 {main} thrown in F:\phpStudy\phpStudy1\WWW\my_project\supervisit\system\database\drivers\pdo\pdo_result.php on line 41