'ConfigurationSettings.AppSettings' is obsolete

Warning CS0618 ‘ConfigurationSettings.AppSettings‘ is obsolete: ‘This method is obsolete, it has been replaced by System.Configuration!System.Configuration.ConfigurationManager.AppSettings‘ 

string _connStr = ConfigurationSettings.AppSettings["DBServer"];

使用以下代码替换上述代码

string _connStr = ConfigurationManager.ConnectionStrings["DBServer"].ToString();

'ConfigurationSettings.AppSettings' is obsolete

原文：https://www.cnblogs.com/LicwStack/p/13508725.html