{"code":0,"msg":"未知操作","data":[]}<br />
<b>Fatal error</b>:  Uncaught Exception: 数据库连接失败: SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: NO) in /www/wwwroot/space.xiliji.teach/space.xiliji.tech/php-backend/utils/DB.php:21
Stack trace:
#0 /www/wwwroot/space.xiliji.teach/space.xiliji.tech/php-backend/utils/DB.php(27): DB-&gt;__construct()
#1 /www/wwwroot/space.xiliji.teach/space.xiliji.tech/php-backend/index.php(16): DB::getInstance()
#2 [internal function]: {closure}()
#3 {main}
  thrown in <b>/www/wwwroot/space.xiliji.teach/space.xiliji.tech/php-backend/utils/DB.php</b> on line <b>21</b><br />