Config

  
    

   
     <
   
     configuration
   
     >
   
     
 
 
   
     <
   
     connectionStrings
   
     >
   
     
 
   
     <
   
     add name
   
     =
   
     "
   
     db_userConnectionString
   
     "
   
      connectionString
   
     =
   
     "
   
     Data Source=WWW-C21CD4737E0;Initial Catalog=db_user;Integrated Security=True
   
     "
   
     
 providerName
   
     =
   
     "
   
     System.Data.SqlClient
   
     "
   
      
   
     />
   
     
 
   
     </
   
     connectionStrings
   
     >
   
     
 
 
   
     <
   
     system.web
   
     >
   
     
 
   
     <
   
     compilation debug
   
     =
   
     "
   
     true
   
     "
   
      targetFramework
   
     =
   
     "
   
     4.0
   
     "
   
      
   
     />
   
     
 
   
     </
   
     system.web
   
     >
   
     


   
     </
   
     configuration
   
     >
  
    

  
    

   
      
   
     <
   
     connectionStrings
   
     >
   
     
 
   
     <
   
     add name
   
     =
   
     "
   
     db_userConnectionString
   
     "
   
      connectionString
   
     =
   
     "
   
     Data Source=WWW-C21CD4737E0;Initial Catalog=db_user;Integrated Security=True
   
     "
   
     
 providerName
   
     =
   
     "
   
     System.Data.SqlClient
   
     "
   
      
   
     />
   
     
 
   
     <!--
   
        
   
     <
   
     add name 
   
     =
   
     "
   
     123
   
     "
   
      connectionString 
   
     =
   
     ""
   
     />
   
     
 
  
 
   
     <
   
     appSettings
   
     >
   
     
 
   
     <
   
     add key
   
     =
   
     "
   
     aa
   
     "
   
      value
   
     =
   
     "
   
     Data Source=WWW-C21CD4737E0;Initial Catalog=db_user;Integrated Security=True
   
     "
   
     />
   
     
 
   
     </
   
     appSettings
   
     >-->
   
     
 
   
     </
   
     connectionStrings
   
     >
  
    

  ：   using System.Configuration;

eg: string str = ConfigurationManager.ConnectionStrings["db_userConnectionString"].ToString();