.net 3.5:从app.config读取连接字符串？

<?xml version="1.0" encoding="utf-8" ?><configuration>
 <connectionStrings>
    <add name="MyConnectionString" connectionString="Data Source=myServerAddress;Initial Catalog=myDataBase;User ID=myUsername;Password=myPassword" />
  </connectionStrings>
</configuration>

using System.Configuration;

string connectionString = ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;