我第一次尝试使用PDO创建一个应用程序,当我try{$db=newPDO('mysql:host=localhost;dbname=DBname','user','pass');}catch(PDOException$e){echo'Failedtoconnecttodatabase.Pleasetrytorefreshthispagein1minute.However,ifyoucontinuetoseethismessagepleasecontactyoursystemadministrator.';echo''.$e->getMessage();exit();}当然,我已经将用户