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一些文件出現錯誤怎么辦

Warning: mysql_connect(): Access denied for user 'root'@'localhost' (using password: YES) inF:\xampp\htdocs\article\connect.php?on line?4
Access denied for user 'root'@'localhost' (using password: YES)Access denied for user ''@'localhost' to database 'info'
Notice: Undefined index: id in?F:\xampp\htdocs\article\article.show.php?on line?3
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出現這個錯誤怎么辦？