C#基礎用戶登陸

1.主界面代碼：

2.注冊頁面

 

 

3.登陸界面

 登陸注冊代碼：

//編寫登錄界面邏輯
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.Data.SqlClient;

namespace LoginDatabase
{
    public partial class Login : Form
    {
        private int errorTime = 3;

        public Login() {
            InitializeComponent();
        }

        private void loginBtn_Click(object sender, EventArgs e) {
            errorTime = errorTime - 1;

            string username = txtName.Text.Trim();  //取出賬號
            string pw = txtPwd.Text.Trim();         //取出密碼
            string constr = "Server=.;DataBase=SU; Integrated Security=True"; //設置連接字符串
            SqlConnection mycon = new SqlConnection(constr);  //實例化連接對象
            mycon.Open();

            SqlCommand mycom = mycon.CreateCommand();         //創建SQL命令執行對象
            string s1 = "select account,password from register where account='" + username + "' and password='" + pw + "'";                                            //編寫SQL命令
            mycom.CommandText = s1;                           //執行SQL命令
            SqlDataAdapter myDA = new SqlDataAdapter();       //實例化數據適配器
            myDA.SelectCommand = mycom;                       //讓適配器執行SELECT命令
            DataSet myDS = new DataSet();                     //實例化結果數據集
            int n = myDA.Fill(myDS, "register");              //將結果放入數據適配器，返回元祖個數
            if (n != 0) {
                if (checkCode.Text == textCheck.Text) { 
                    MessageBox.Show("歡迎使用！");             //登錄成功
                    this.Close();
                } else {
                    MessageBox.Show("驗證碼填寫錯誤");
                    textCheck.Text = "";
                }
            } else
                if (errorTime < 3) {
                    MessageBox.Show("用戶名或密碼有錯。請重新輸入！還有" + errorTime.ToString() + "次機會");
                    txtName.Text = "";   //清空賬號
                    txtPwd.Text = "";    //清空密碼?
                    txtName.Focus();     //光標設置在賬號上
                } else {
                    MessageBox.Show("你輸入的用戶名或密碼已達三次? 將退出程序");
                    this.Close();
                }

        }

        private void cancelBtn_Click(object sender, EventArgs e) {
            Application.Exit();
        }

        private void button1_Click(object sender, EventArgs e) {
            Register register = new Register();
            register.ShowDialog();
        }

        private void checkCode_Click(object sender, EventArgs e) {
            Random random = new Random();
            int minV = 12345, maxV = 98765;
            checkCode.Text = random.Next(minV, maxV).ToString();
        }
    }
}

5.編寫注冊界面邏輯
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace LoginDatabase
{
    public partial class Register : Form
    {
        public Register() {
            InitializeComponent();
        }

        private void btnRegister_Click(object sender, EventArgs e) {

            //檢查是否已經存在
            string userID = userId.Text.Trim();  //取出賬號
            
            /**
             * 連接數據庫
             */ 
            string constr = "Server=.;DataBase=SU; Integrated Security=True"; //設置連接字符串
            SqlConnection mycon = new SqlConnection(constr);                  //實例化連接對象
            mycon.Open();


            //查詢新注冊的用戶是否存在
            SqlCommand checkCmd = mycon.CreateCommand();       //創建SQL命令執行對象
            string s = "select account from register where account='" + userID + "'";
            checkCmd.CommandText = s;
            SqlDataAdapter check = new SqlDataAdapter();       //實例化數據適配器
            check.SelectCommand = checkCmd;                    //讓適配器執行SELECT命令
            DataSet checkData = new DataSet();                 //實例化結果數據集
            int n = check.Fill(checkData, "register");         //將結果放入數據適配器，返回元祖個數
            if (n != 0) {
                MessageBox.Show("用戶名存在");
                userId.Text = ""; userPw.Text = "";
                nickName.Text = "";
            }
     

            //確認密碼
            if (ensurePw.Text != userPw.Text) {
                ensurePw.Text = "";
            }

            //驗證碼
            if (textCheck.Text != checkCode.Text) {
                textCheck.Text = "";
            }

            //插入數據SQL  邏輯
            string s1 = "insert into Register(account,password,nickname) values ('" + userId.Text + "','" + userPw.Text + "','"
                + nickName.Text + "')";                            //編寫SQL命令
            SqlCommand mycom = new SqlCommand(s1, mycon);          //初始化命令
            mycom.ExecuteNonQuery();             //執行語句
            mycon.Close();                       //關閉連接
            mycom = null;
            mycon.Dispose();                     //釋放對象


            if (userId.Text == "" || userPw.TextLength <= 6 || nickName.Text == "" || ensurePw.Text == ""
                || textCheck.Text == "") {
                MessageBox.Show("請將信息填完整");
            } else {
                MessageBox.Show("注冊成功");
                this.Close();
            }
        }

        private void checkCode_Click(object sender, EventArgs e) {
            Random random = new Random();
            int minV = 12345, maxV = 98765;
            checkCode.Text = random.Next(minV, maxV).ToString();
        }
    }