C#简单验证并限制登录次数小示例

描述：提示用户输入用户名，密码，与数据库中的数据匹配，如果正确则提示登陆成功，否则，提示登陆失败错误次数超过三次，提示登陆次数过多，禁止登陆
数据表示例：
 1 //数据库中ErrorTimes的次数增加1
 2 public void incError()
 3         {
 4             using (SqlConnection conn = new SqlConnection(@"Data Source=.SQLEXPRESS;AttachDBFilename=|DataDirectory|Database1.mdf;Integrated Security=True;User Instance=True"))
 5             {
 6                 conn.Open();
 7                 SqlCommand cmd1 = conn.CreateCommand();
 8                 cmd1.CommandText = "update T_Users set ErrorTimes=ErrorTimes+1 where UserName=@UN";
 9                 cmd1.Parameters.Add(new SqlParameter("UN", txtUsername.Text));
10                 cmd1.ExecuteNonQuery();
11                  
12             }
13         }
14 //重置数据库中ErrorTimes的次数为0
15         public void clsError()
16         {
17             using (SqlConnection conn = new SqlConnection(@"Data Source=.SQLEXPRESS;AttachDBFilename=|DataDirectory|Database1.mdf;Integrated Security=True;User Instance=True"))
18             {
19                 conn.Open();
20                 SqlCommand cmd1 = conn.CreateCommand();
21                 cmd1.CommandText = "update T_Users set ErrorTimes=0 where UserName=@UN";
22                 cmd1.Parameters.Add(new SqlParameter("UN", txtUsername.Text));
23                 cmd1.ExecuteNonQuery();
24  
25             }
26  
27        private void button1_Click(object sender, EventArgs e)
28         {
29             //提示用户输入用户名，密码，与数据库中的数据匹配，如果正确则提示登陆成功，否则，提示登陆失败
30             ///错误次数超过三次，提示登陆次数过多，禁止登陆。
31             using (SqlConnection conn = new SqlConnection(@"Data Source=.SQLEXPRESS;AttachDBFilename=|DataDirectory|Database1.mdf;Integrated Security=True;User Instance=True"))
32             {
33                 conn.Open();
34                 SqlCommand cmd = conn.CreateCommand();
35                 cmd.CommandText = "select * from T_Users where UserName=@UN";
36                 cmd.Parameters.Add(new SqlParameter("UN", txtUsername.Text));
37                 using (SqlDataReader reader = cmd.ExecuteReader())
38                 {
39                     if (reader.Read())
40                     {
41                         int errortimes = reader.GetInt32(reader.GetOrdinal("ErrorTimes"));
42                         if (errortimes > 3)
43                         {
44                             MessageBox.Show("错误次数过多，禁止登陆");
45                         }
46                         string dbpassword = reader.GetString(reader.GetOrdinal("PassWord"));
47                         if (dbpassword == txtPassword.Text)
48                         {
49                             MessageBox.Show("登陆成功");
50                             clsError();
51                         }
52                         else
53                         {
54                             incError();
55                             MessageBox.Show("登陆失败");
56                             
57                         }
58                     }
59                     else
60                     {
61                         MessageBox.Show("用户名不存在");
62                     }