using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Configuration;

using System.Data.SqlClient;

namespace 使用者登入

{

    public partial class Form1 : Form

    {

        publicForm1()

        {

            InitializeComponent();

        }

        ///<summary>

        ///增加錯誤次數的方法

        ///</summary>

        privatevoid IncErrorTime()

        {

            stringConnStr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;

            using

            {

                using(SqlCommand updateCmd =conn.CreateCommand())

                {

                    updateCmd.CommandText = "update T_Admin set errortime=errortime+1 [email protected]";

                    updateCmd.Parameters.Add(new

                    conn.Open();

                    updateCmd.ExecuteNonQuery();

                }           

            } 

        }

        ///<summary>

        ///錯誤次數清0

        ///</summary>

        privatevoid NotErrorTime()

        {

            stringConnStr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;

            using(SqlConnection conn = new SqlConnection(ConnStr))

            {

                using(SqlCommand updateCmd =conn.CreateCommand())

                {

                    updateCmd.CommandText = "update T_Admin set errortime=0 [email protected]";

                    updateCmd.Parameters.Add(new SqlParameter("username", txtUserName.Text));

                    conn.Open();

                   updateCmd.ExecuteNonQuery();

                }

            }

        }

        ///<summary>

        ///密碼錯誤3次,記錄當前時間加30分鐘

        ///</summary>

        privatevoid IncLoginTime()

        {

            stringConnStr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;

            using(SqlConnection conn = new SqlConnection(ConnStr))

            {

                using(SqlCommand updateCmd =conn.CreateCommand())

                {

                    updateCmd.CommandText = "update T_Admin set [email protected] [email protected]";

                    DateTimelogintime = DateTime.Now.AddMinutes(30);

                    updateCmd.Parameters.Add(new SqlParameter("username", txtUserName.Text));

                    updateCmd.Parameters.Add(new SqlParameter("logintime", logintime.ToString()));

                    conn.Open();

                   updateCmd.ExecuteNonQuery();

                }

            }

        }

        privatevoid button1_Click(objectsender, EventArgs e)

        {

            stringusername = txtUserName.Text;

            stringpassword = txtPassword.Text;                       

            stringConnStr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;

            using(SqlConnection conn = new SqlConnection(ConnStr))

            {

                using(SqlCommand cmd = conn.CreateCommand())

                {

                    cmd.CommandText = "select * from T_Admin [email protected]";

                    cmd.Parameters.Add(new SqlParameter("username", username));                  

                    conn.Open();

                    using(SqlDataReader reader = cmd.ExecuteReader())

                    {

                        if (reader.Read())

                        {

                            //使用者存在

                            string dbpassword =reader.GetString(reader.GetOrdinal("password"));

                            DateTime logintime =reader.GetDateTime(reader.GetOrdinal("logintime"));

                            //判斷當前時間是是伺服器允許登入時間

                            if (logintime > DateTime.Now)

                            {

                                MessageBox.Show("一定時間內禁止登入");

                                return;

                            }

                            //如果密碼正確

                            if (dbpassword == txtPassword.Text)

                            {

                                NotErrorTime();

                                MessageBox.Show("登入成功!");

                            }

                            //如果密碼錯誤

                            else

                            {

                                int errortime = reader.GetInt32(reader.GetOrdinal("errortime"));

                                if (errortime >= 2)

                                {

                                    MessageBox.Show("密碼錯誤次數太多!");

                                   IncLoginTime();

                                   NotErrorTime();

                                    return;

                                }                               

                                MessageBox.Show("密碼錯誤!");

                                IncErrorTime();//密碼錯誤,次數加1

                            }

                        }

                        else//使用者名稱不存在

                        {                           

                            MessageBox.Show("使用者名稱不存在!");

                            return;

                        }

                    }                   

                }

            }

        }

    }

}