数据库：

项目的数据模块图：

BLL层：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Login.DAL;
using Login.Model;
namespace Login.BLL
{
    public class UserinfoBLL
    {
        UserInfoDAL userInfoDal = new UserInfoDAL();
        public int Login(UserInfo user)
        {
            int count = userInfoDal.UserLogin(user);
            return count;
        }
    }
}

DAL层：

using Login.Model;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;
using Login.DBHelper;
namespace Login.DAL
{
    public class UserInfoDAL
    {
        SQLHelper sqlHelp = new SQLHelper();
        public int UserLogin(UserInfo user)
        {
            int i = Convert.ToInt32(sqlHelp.ExecuteScalar("select count(*) from T_login where username=@UserName and password=@PassWord",
                 new SqlParameter("@UserName", user.userName),
                  new SqlParameter("@PassWord", user.password)));
            return i;
        }
    }
}

Model层（Entity类）：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Login.Model
{
    public class UserInfo
    {
        public string userName { get; set; }
        public string password { get; set; }
    }
}

UI层：

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 Login.Model;
using Login.BLL;
namespace Login
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        UserInfo user = new UserInfo();
        UserinfoBLL userBll = new UserinfoBLL();
        private void button1_Click(object sender, EventArgs e)
        {
            user.userName = textBox1.Text.Trim();
            user.password = textBox2.Text.Trim();
            if (user.userName == "")
            {
                MessageBox.Show("请输入用户名!");
                return;
            }
            if (user.password == "")
            {
                MessageBox.Show("请输入密码!");
                return;
            }
            int count = userBll.Login(user);
            if (count>0)
            {
                MessageBox.Show("登录成功");
            }
            else
            {
                MessageBox.Show("用户名密码错误");
            }
        }
    }
}

还有数据库访问类（SQLHelper.cs）代码太多就不贴出来了

GitHub源码下载：https://github.com/kiritobin/LoginThreeFram

原文链接：https://www.idaobin.com/archives/1074.html

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