ConfigurationManager类

       今天在更改以前的数据库操作类时突然发现ConfigurationSettings类不能用了，却被编译器提示说：警告  1 “System.Configuration.ConfigurationSettings.AppSettings”已过时:“This method is obsolete, it has been replaced by System.Configuration!System.Configuration.ConfigurationManager.AppSettings”

于是转而想找到那个ConfigurationManager类来使用，结果在System.Configuration命名空间下死活找不到 ConfigurationManager类，无奈，求助于网络，才知道原来还要添加对System.Configuration.dll 文件的引用~~

事后才留意到，原来MS对这一点还是提示了一下的，只不过比较隐晦而已——
This method is obsolete, it has been replaced by System.Configuration!System.Configuration.ConfigurationManager.AppSettings
注意到没有，上面这段话多了System.Configuration!这段

````````````````````````````````````````````````````
VS2005里读取WEB应用的config文件中的数据库链接的写法：

CONFIG文件中：
<appSettings/>
<connectionStrings>
<add name="DatabaseConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True"
providerName="System.Data.SqlClient" />
</connectionStrings>

程序中
System.Web.Configuration.WebConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;