.net简单的三层实现功能

在网上看到别人的代码,写下来留着看,欢迎各位指教,有没有工厂模式的学习资料啊,留下给小弟学习学习.
首先写个Model类，实现业务实体，我的比较简单，只有三个字段
  View Code
 1  public class LoginModel
 2     {
 3         #region
 4
 5         private int _AdminId;
 6         private string _AdminUID;
 7         private string _AdminPWD;
 8
 9         public string AdminPWD
10         {
11             get { return _AdminPWD; }
12             set { _AdminPWD = value; }
13         }
14
15         public int AdminId
16         {
17             get { return _AdminId; }
18             set { _AdminId = value; }
19         }
20       
21
22         public string AdminUID
23         {
24             get { return _AdminUID; }
25             set { _AdminUID = value; }
26         }
27
28         #endregion
29     }

2.创建一个DBHelp类，实现SQLServer数据库访问
  View Code
  1 public class DBHelp
  2     {
  3         private static readonly string connectionString = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString.ToString();
  4         private static readonly string providerName = "System.Data.SqlClient";
  5
  6         /// <summary>
  7         /// GetConnection 用于获取连接数据库的 connection 对象
  8         /// </summary>
  9         /// <returns></returns>
 10         private static DbConnection GetConnection()
 11         {