简单窗体登陆验证

连续登陆失败3次之后，账户锁定，15分钟之内不能登陆

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;
using System.Data.SqlClient;

namespace LoginLockDemo
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            //拿到连接字符串
            string sql = ConfigurationManager.ConnectionStrings["SqlConn"].ConnectionString;
            //创建连接数据库
            using (SqlConnection conn = new SqlConnection(sql))
            {
                //创建sql命令
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.Connection = conn;
                    conn.Open();//打开数据库

            //cmd.CommandText = string.Format("select * from Lduser where name='{0}' and pwd='{1}'", txtName.Text.Trim(), txtPwd.Text.Trim());
               //解决sql注入漏洞
                     cmd.CommandText ="select * from Lduser where name=@Username and pwd=@UserPwd";
                    cmd.Parameters.AddWithValue("@UserName", txtName.Text.Trim());
                       cmd.Parameters.AddWithValue("@UserPwd", txtPwd.Text.Trim());

                    User user = new User();

using (SqlDataReader reader = cmd.ExecuteReader())
                    {

                        if (reader.Read())//如果能查询出来,再判断登陆次数和登陆时间
                        {
                            user.LastErrorTime = DateTime.Parse(reader["LastErrorDateTime"] == DBNull.Value ? DateTime.MinValue.ToString() : reader["LastErrorDateTime"].ToString());
                            user.ErrorTimes = int.Parse(reader["ErrorTimes"] == DBNull.Value ? int.MinValue.ToString() : reader["ErrorTimes"].ToString());
                            TimeSpan span = (TimeSpan)(DateTime.Now - user.LastErrorTime);
                            if (span.TotalMinutes > 15 || user.ErrorTimes < 3)//如果上次登陆失败时间和失败次数小于3次，那么就可以登陆
                            {
                                //如果登陆成功了，就将登陆失败次数清零
                                cmd.CommandText = string.Format("update Lduser set ErrorTimes=0 where name='{0}'", txtName.Text.Trim());
                                reader.Close();//关闭当前SqlDataReader对象，将conn释放出来
                                cmd.ExecuteNonQuery();
                                MessageBox.Show("登陆成功");
                                return;
                            }
                            else
                            {
                                MessageBox.Show("账户被锁定中，登陆失败");
                                return;
                            }
                        }
                    }
                    //查询不到数据,退出当前SqlDataReader对象

                    //在查询有没有当前用户
                    cmd.CommandText = string.Format("select * from Lduser where name='{0}'", txtName.Text.Trim());
                    using (SqlDataReader reader = cmd.ExecuteReader())
                    {
                        if (reader.Read())//如果有当前用户
                        {
                            cmd.CommandText = string.Format("update Lduser set ErrorTimes={0},LastErrorDateTime=GETDATE() where name='{1}'", int.Parse(reader["ErrorTimes"].ToString()) + 1, txtName.Text.Trim());
                            reader.Close();//关闭当前SqlDataReader对象，将conn释放出来
                            cmd.ExecuteNonQuery();
                            MessageBox.Show("密码错误,登陆失败");
                        }
                        else//如果没有当前用户
                        {
                            MessageBox.Show("当前用户不存在");
                        }
                    }
                }
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace LoginLockDemo
{
    class User
    {
        public string Name { get; set; }
        public string Password { get; set; }
        public DateTime LastErrorTime { get; set; }
        public int ErrorTimes { get; set; }
    }
}

USE [LdbDemo]
GO
/****** Object:  Table [dbo].[Lduser]    Script Date: 2017/3/22 22:38:15 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Lduser](
    [lid] [int] IDENTITY(1,1) NOT NULL,
    [name] [nvarchar](16) NOT NULL,
    [pwd] [nvarchar](32) NOT NULL,
    [age] [int] NULL,
    [CreateDate] [datetime] NULL,
    [LastErrorDateTime] [datetime] NULL,
    [ErrorTimes] [int] NULL
) ON [PRIMARY]

GO