Warning: include_once(environment.dev.php): Failed to open stream: No such file or directory in /var/www/html/conventionroadshow/admin/delegate-import.php on line 8

Warning: include_once(): Failed opening 'environment.dev.php' for inclusion (include_path='.:/usr/share/php') in /var/www/html/conventionroadshow/admin/delegate-import.php on line 8
INSERT INTO delegate (`delegate_code`,`is_minor`,`meal_preference`,`group_code`,`group_contact`) VALUES('XVYWB2QPK9N',0,'Standard','346K444JQJNR',0);

Fatal error: Uncaught Error: Undefined constant "MYSQL_USERNAME" in /var/www/html/conventionroadshow/app/core/class.DB.php:23 Stack trace: #0 /var/www/html/conventionroadshow/app/core/class.DB.php(42): Database->connect() #1 /var/www/html/conventionroadshow/admin/delegate-import.php(58): Database->query() #2 {main} thrown in /var/www/html/conventionroadshow/app/core/class.DB.php on line 23