Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000] [2005] Unknown MySQL server host 'rdsoe7ln09bdo4wwli49rw.mysql.rds.aliyuncs.com' (1)' in /var/www/html/train_dev/framework/class/db.class.php:55 Stack trace: #0 /var/www/html/train_dev/framework/class/db.class.php(55): PDO->__construct('mysql:dbname=ty...', 'tysd_train', 'tysd_school8070', Array) #1 /var/www/html/train_dev/framework/class/db.class.php(25): DB->connect('master') #2 /var/www/html/train_dev/framework/function/pdo.func.php(22): DB->__construct('master') #3 /var/www/html/train_dev/framework/function/pdo.func.php(36): pdo() #4 /var/www/html/train_dev/framework/function/cache.mysql.func.php(13): pdo_fetchcolumn('SELECT `value` ...', Array) #5 /var/www/html/train_dev/framework/function/cache.func.php(31): cache_read('setting') #6 /var/www/html/train_dev/framework/model/setting.mod.php(35): cache_load('setting') #7 /var/www/html/train_dev/framework/bootstrap.inc.php(116): setting_load() #8 /var/www/html/train_dev/web/index.php(7): require in /var/www/html/train_dev/framework/class/db.class.php on line 55