简单的系统登录功能

 一、登录界面及更改密码界面



二、创建存储过程
1、pr_login

CREATE  proc  pr_login
@id varchar(10),            --输入参数
@pwd varchar(10),           --输入参数
@result varchar(10) output  --输出参数
as
select * from login where 登录工号=@id
if(@@rowcount<1)
   begin 
     set @result='没有此工号'
   end
else
   begin 
     select * from login where (登录工号=@id)and(登录密码=@pwd)
     if(@@rowcount<1)
        begin 
          set @result='密码错误'
        end
     else 
        begin
          set @result='ACCESS'
        end
   end
return

2、pr_OperateLogin

CREATE  proc pr_OperateLogin
@id varchar(10),
@pwd varchar(10),
@filter char(10)
as
if(@filter='普通查询')
   select 登录工号 from login --用来加载工号
else if(@filter='按工号查询')
       select 登录工号,登录密码 from login where 登录工号=@id --用来判断密码输入的正确与否
else if(@filter='更新密码')  --更改密码
          update login set 登录密码=@pwd where 登录工号=@id
return

三、创建类LinkDB.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;
using System.Data.SqlTypes;

namespace BookSale
{
    class LinkDB
    {
        SqlConnection conn = new SqlConnection("server=localhost;integrated security=sspi;database=library"); //连接的是本地数据库

        //调用存储过程判断是否登录成功(bllogin为true表示登录成功；为false表示登录失败)
        public bool Login(string strid, string strpwd)
        {
            bool bllogin = false;
            SqlCommand cmd = new SqlCommand("pr_login",conn);
            cmd.CommandType = CommandType.StoredProcedure;

            cmd.Parameters.Add("@id",SqlDbType.VarChar,10).Value=strid;//输入参数
            cmd.Parameters.Add("@pwd", SqlDbType.VarChar, 10).Value = strpwd;//输入参数

            SqlParameter ParameterResult = new SqlParameter("@result",SqlDbType.VarChar,10);
            ParameterResult.Direction = ParameterDirection.Output; //输出参数
            cmd.Parameters.Add(ParameterResult);

            conn.Open();
            cmd.ExecuteNonQuery();
            conn.Close();

            if (ParameterResult.Value.ToString().Trim() == "ACCESS")
            {
                bllogin = true;
            }
            if (ParameterResult.Value.ToString().Trim() == "没有此工号")
            {
                bllogin = false;
                MessageBox.Show("输入的工号错误(工号不能为空),请输入正确的工号!","提示",MessageBoxButtons.OK,MessageBoxIcon.Information);
            }
            if(ParameterResult.Value.ToString().Trim()=="密码错误")
            {
                bllogin = false;
                MessageBox.Show("输入的密码错误(密码不能为空),请重新输入!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            return bllogin;
        }

        //用来查询，供加载登录工号和判断密码是否正确(有返回值)
        public DataTable queryLogin(string str_id,string str_pwd,string str_Filter)
        {
            SqlCommand cmd = new SqlCommand("pr_OperateLogin", conn);
            cmd.CommandType = CommandType.StoredProcedure;

            cmd.Parameters.Add("@id", SqlDbType.VarChar, 10).Value = str_id;
            cmd.Parameters.Add("@pwd", SqlDbType.VarChar, 10).Value = str_pwd;
            cmd.Parameters.Add("@filter",SqlDbType.Char,10).Value=str_Filter;
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            da.Fill(dt);
            return dt;
        }

        
        //用来修改用户密码(无返回值) 
        public void updateLogin(string str_id,string str_pwd,string str_Filter)
        {
            SqlCommand cmd = new SqlCommand("pr_OperateLogin",conn);
            cmd.CommandType = CommandType.StoredProcedure;

            cmd.Parameters.Add("@id", SqlDbType.VarChar, 10).Value = str_id;
            cmd.Parameters.Add("@pwd", SqlDbType.VarChar, 10).Value = str_pwd;
            cmd.Parameters.Add("@filter", SqlDbType.Char, 10).Value = str_Filter;
            conn.Open();
            cmd.ExecuteNonQuery();
            conn.Close();
        }
    }
}

四、loginFrm.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace BookSale
{
    public partial class loginFrm : Form
    {
        public loginFrm()
        {
            InitializeComponent();
        }
        //------退出------
        private void btnexit_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        LinkDB linkDB = new LinkDB();
        DataTable dt;
        private void loginFrm_Load(object sender, EventArgs e)
        {
            this.AcceptButton = this.btnenter; //按Enter键对应登录键
            this.CancelButton = this.btnexit;
            string strid = "";
            string strpwd = "";
            string strFilter = "普通查询";
            dt = linkDB.queryLogin(strid,strpwd,strFilter);
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                this.cmbid.Items.Add(dt.Rows[i][0]);
            }
        }

        //------登录------
        public static bool str_pass = false;
        public bool blpass = false;
        private void btnenter_Click(object sender, EventArgs e)
        {
            string str_id = this.cmbid.Text.ToString().Trim();
            string str_pwd = this.txtpwd.Text.ToString().Trim();
            blpass = linkDB.Login(str_id, str_pwd);
            if (blpass == false)
            {
                this.txtpwd.Clear();
                this.cmbid.Focus();
                return;
            }
            this.Close();
        }

        //------更改密码------
        private void btnmodify_Click(object sender, EventArgs e)
        {
            modifyFrm modifyForm = new modifyFrm();
            modifyForm.Show();
        }
    }
}

五、modifyFrm.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace BookSale
{
    public partial class modifyFrm : Form
    {
        public modifyFrm()
        {
            InitializeComponent();
        }

        private void btnexit_Click(object sender, EventArgs e)
        {
            this.Close();
        } 

        LinkDB linkDB = new LinkDB();
        DataTable dt1;  //用来存放所有的登录工号
        DataTable dt2;  //用来存放筛选出来的登录工号、登录密码
        private void modifyFrm_Load(object sender, EventArgs e)
        {
            Loading1();
            for (int i = 0; i < dt1.Rows.Count; i++)
            {
                this.cmbid.Items.Add(dt1.Rows[i][0]);
            }
        }

        //加载登录工号
        protected void Loading1()
        {
            string strid = "";
            string strpwd = "";
            string strfilter1 = "普通查询";
            dt1 = linkDB.queryLogin(strid, strpwd, strfilter1);  
        }

        //加载筛选出来的登录工号、登录密码
        protected void Loading2()
        {
            string strid = this.cmbid.Text.ToString().Trim();
            string strpwd = "";
            string strfilter2 = "按工号查询";
            dt2 = linkDB.queryLogin(strid, strpwd, strfilter2);
        }

        //------更改按钮------
        private void btnmodify_Click(object sender, EventArgs e)
        {
            string str_id = this.cmbid.Text.ToString().Trim();
            if (str_id == "")  //工号为空
            {
                MessageBox.Show("工号不为空!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                this.cmbid.Focus();
                return;
            }
            if (this.cmbid.Text.ToString().Trim() != "")  //工号不为空，则判断工号是否输入正确
            {
                Loading2();
                if (dt2.Rows.Count!=0) //工号输入正确
                {
                    if (this.txtpwd.Text.ToString().Trim() == "")  //密码为空
                    {
                        MessageBox.Show("密码不能为空!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                        this.txtpwd.Focus();
                        return;
                    }
                    else  //密码不为空，则判断密码是否输入正确
                    {

                        if (this.txtpwd.Text.ToString().Trim() == dt2.Rows[0][1].ToString().Trim()) //密码正确
                        {
                            if (this.txtnewpwd.Text.ToString().Trim() == "" || this.txtnewpwd_again.Text.ToString().Trim() == "")  //新密码和确认密码不能为空
                            {
                                MessageBox.Show("新密码和确认密码不能为空!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                                this.txtnewpwd.Focus();
                                return;
                            }
                            else //新密码和确认密码都不为空，则判断新密码和确认密码是否一致
                            {
                                if (this.txtnewpwd.Text.ToString().Trim() == this.txtnewpwd_again.Text.ToString().Trim()) //新密码和确认密码一致
                                {
                                    string strid = this.cmbid.Text.ToString().Trim();
                                    string strpwd = this.txtnewpwd.Text.ToString().Trim();
                                    string strfilter3 = "更新密码";
                                    linkDB.updateLogin(strid, strpwd, strfilter3);
                                    MessageBox.Show("密码修改成功!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                                    this.txtpwd.Clear();
                                    this.txtnewpwd.Clear();
                                    this.txtnewpwd_again.Clear();
                                    return;
                                }
                                else  //新密码和确认密码不一致
                                {
                                    MessageBox.Show("2次输入的密码不一致,请重新输入新密码和确认密码!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                                    this.txtnewpwd.Clear();
                                    this.txtnewpwd_again.Clear();
                                    this.txtnewpwd.Focus();
                                    return;
                                }
                            }
                        }
                        else  //密码输入错误
                        {
                            MessageBox.Show("输入的密码不正确!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                            this.txtpwd.Clear();
                            this.txtpwd.Focus();
                            return;
                        }
                    }
                }
                else  //工号输入错误
                {
                    MessageBox.Show("输入的工号错误,请输入正确的工号!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    return;
                }
            }
        }
    }
}

六、Programe.cs

using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace BookSale
{
    static class Program
    {
        /**//// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
           
            loginFrm loginForm = new loginFrm();
            loginForm.ShowDialog();
            if (loginForm.blpass==true)
            {
                Application.Run(new mainFrm());
            }
        }
    }
}

七、创建数据库

use master
go 
create database library
go 
create table login
(登录工号 varchar(10),
 登录密码 varchar(10)
)
go
insert into login values('DEMO','admin')
go 

PS：以上程序写的比较粗糙，有什么不妥的地方，请大家给予指正。