Winform login + verification code + link database + window switching

Login window: Form_login.cs

Database link class: SQLhelper.cs (sqlserver used)

User class: LoginUser.CS

Verification code: UpdateCode.cs

Login window Form_login.cs

using MedicalRecord.Class;
using System;
using System.Windows.Forms;
namespace MedicalRecord
{
    public partial class Form_login : DevComponents.DotNetBar.OfficeForm
    {
        //Database link class and user class
        private SQLhelper sqLhelper = new SQLhelper();
        private static LoginUser LoginUser = new LoginUser ();
        private string code = String.Empty;
        public Form_login()
        {
            InitializeComponent();
        }

        //login button
        private void Login_Click(object sender, EventArgs e)
        {
            // Determine whether the input is empty, if it is empty, you need to remind
            // Determine if an account is entered
            if (string.IsNullOrEmpty(this.Skin_usercode.Text))
            {
                MessageBox.Show("Username must be entered!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Skin_usercode.Focus();
                return;
            }
            // Determine whether to enter a password
            if (string.IsNullOrEmpty(Skin_password.Text))
            {
                MessageBox.Show("Password must be entered!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Skin_password.Focus();
                return;
            }
            //If not, assign the input to the loginuser class
            LoginUser.Usercode = Skin_usercode.Text;
            LoginUser.Password = Skin_password.Text;

            //To access the database, check whether the user exists
            string selectSql =
                string.Format("select  count(*) from mris.dbo.sys_user where usercode = '{0}'   and password = '{1}' ",
                    LoginUser.Usercode, LoginUser.Password);
            //Accept database return information
            //ExecuteScalar executes a SqlCommand command that returns the first column of the first record
            int ss = (int) sqLhelper.ExecuteScalar(selectSql);
            //If it exists, it will DialogResult.OK, otherwise the prompt does not exist
            if (ss == 1)
            {
                this.DialogResult = DialogResult.OK;
            }
            else
            {
                MessageBox.Show("User password does not exist!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Skin_password.Clear();
                Skin_usercode.Clear();
                Skin_usercode.Focus();
                return;
            }
        }
        // Generate a verification code when the window opens
        private void Form_login_Load(object sender, EventArgs e)
        {
            change();
        }
        private void cde_Click(object sender, EventArgs e)
        {
            change();
        }
        private void cde_DoubleClick(object sender, EventArgs e)
        {
            change();
        }
        public void change()
        {
            UpdateCode updateCode = new UpdateCode();
            code = updateCode.MakeRandomCode(4);
            this.cde.Image = updateCode.MakeImage(code, this.cde.Width, this.cde.Height);
        }
    }
}

User class: LoginUser.CS

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

namespace MedicalRecord.Class
{
    public  class LoginUser
    {
        private string _usercode;
        public string Usercode
        {
            get { return _usercode; }
            set { _usercode = value; }
        }
        private string _password;

        public string Password
        {
            get { return _password; }
            set { _password = value; }
        }
    }
}

Verification code: UpdateCode.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;

namespace MedicalRecord.Class
{
    public class UpdateCode
    {
        public string  MakeRandomCode(int codelenght)
        {
            return CreateRandomCode(codelenght);
        }

        public Bitmap MakeImage(string codestring ,int width ,int height)
        {
            return CreateImage(codestring, width, height);
        }
        private string CreateRandomCode(int codelenght)
        {
            int rand;
            char code;
            String RandomCode = String.Empty;
            Random random = new Random();
            for (int i = 0; i < codelenght; i++)
            {
                rand = random.Next();
                if (rand%3 == 0)
                {
                    code = (char) ('A' + (char) (rand%26));
                }
                if (rand%3 == 1)
                {
                    code = (char) ('a' + (char) (rand%26));
                }
                else
                {
                    code = (char) ('0' + (char) (rand%10));
                }
                RandomCode += code;
            }
            return RandomCode;
        }

        private Bitmap CreateImage(string RandCode ,int width ,int height )
        {
            Bitmap map = new Bitmap(width, height);
            Graphics graph = Graphics.FromImage(map);
            graph.Clear(Color.AliceBlue);
            graph.DrawRectangle(new Pen(Color.Black, 0), 0, 0, width - 1, height - 1); //画一个边框
            graph.SmoothingMode = SmoothingMode.AntiAlias; //
            Random rand = new Random();
            //背景噪点生成
            Pen blackpen = new Pen(Color.Gray, 0);

            for (int i = 0; i < 50; i++)
            {
                int y = rand.Next(0, height);
                int x = rand.Next(0, width);
                graph.DrawRectangle(blackpen, x, y, 1, 1);
            }
            //文字距中
            char[] chars = RandCode.ToCharArray();
            StringFormat format = new StringFormat(StringFormatFlags.NoClip);
            format.Alignment = StringAlignment.Center;
            format.LineAlignment = StringAlignment.Center;
            //定义字体
            Color[] c =
            {
                Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan,
                Color.Purple
            };
            string[] font = {"Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体"};
            for (int i = 0; i < chars.Length; i++)
            {
                int cindex = rand.Next(7);
                int findex = rand.Next(5);
                Font f = new Font(font[findex], 13, FontStyle.Bold); //字体样式(参数2为字体大小)
                Brush b = new SolidBrush(c[cindex]);
                Point dot = new Point(16, 16);
                float angle = rand.Next(-45, 45); //转动的度数
                graph.TranslateTransform(dot.X, dot.Y); //移动光标到指定位置
                graph.RotateTransform(angle);
                graph.DrawString(chars[i].ToString(), f, b, 1, 1, format);
                graph.RotateTransform(-angle); //转回去
                graph.TranslateTransform(2, -dot.Y); //移动光标到指定位置
            }
            return map  ;
        }
    }
}

数据库链接类 :SQLhelper.cs

using System.Data;
using System.Data.SqlClient;

namespace MedicalRecord.Class
{
    internal class SQLhelper
    {
        private static readonly string DateSource = "(Local)";
        private static readonly string Initial = "";//写库名
        private static readonly string User = "sa";
        private static readonly string Password = " ";//写密码

        private static readonly string connectionString =
            string.Format(
                "Data Source={0};Pooling=False;Max Pool Size = 1024;Initial Catalog={1};Persist Security Info=True;User ID={2};Password={3}",
                DateSource, Initial, User, Password);

        public static SqlConnection conn;
        //打开数据库连接
        public static void OpenConn()
        {
            conn = new SqlConnection(connectionString);
            if (conn.State.ToString().ToLower() != "open")
            {
                conn.Open();
            }
        }
        //关闭数据库连接
        public static void CloneConn()
        {
            if (conn.State.ToString().ToLower() != "open")
            {
                conn.Close();
                conn.Dispose();
            }
        }
        // 读取数据
        public static SqlDataReader GetDataReaderValue(string sql)
        {
            OpenConn();
            SqlCommand command = new SqlCommand(sql, conn);
            SqlDataReader dataReader = command.ExecuteReader();
            CloneConn();
            return dataReader;
        }
        // 返回DataSet
        public DataSet GetDataSetValue(string sql, string tablename)
        {
            OpenConn();

            DataSet dataSet = new DataSet();
            SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sql, conn);
            sqlDataAdapter.Fill(dataSet, tablename);
            CloneConn();
            return dataSet;
        }
        //  返回DataView
        public DataView GetDataViewVaule(string sql)
        {
            OpenConn();
            SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sql, conn);
            DataSet dataSet = new DataSet();
            sqlDataAdapter.Fill(dataSet, "temp");
            CloneConn();
            return dataSet.Tables[0].DefaultView;
        }

        //  返回DataView
        public DataTable GetDataTableValue(string sql)
        {
            OpenConn();
            SqlDataAdapter sqlDataAdapter = new SqlDataAdapter();
            DataTable dataTable = new DataTable();
            sqlDataAdapter.Fill(dataTable);
            CloneConn();
            return dataTable;
        }

        // 执行一个SQL操作:添加、删除、更新操作
        public void ExecuteNonQuery(string sql)
        {
            OpenConn();
            SqlCommand command = new SqlCommand(sql, conn);
            command.ExecuteNonQuery();
            command.Dispose();
            CloneConn();
        }

        // 执行一个SQL操作:添加、删除、更新操作，返回受影响的行
        public int ExecuteNonQueryCount(string sql)
        {
            OpenConn();
            SqlCommand cmd = new SqlCommand(sql, conn);
            int value = cmd.ExecuteNonQuery();
            return value;
        }

        //执行一条返回第一条记录第一列的SqlCommand命令
        public object ExecuteScalar(string sql)
        {
            OpenConn();
            SqlCommand cmd = new SqlCommand(sql, conn);
            object value = cmd.ExecuteScalar();
            return value;
        }

        // 返回记录数
        public int SqlServerRecordCount(string sql)
        {
            OpenConn();
            SqlCommand cmd = new SqlCommand(sql, conn);
            SqlDataReader dr = cmd.ExecuteReader();
            int RecordCount = 0;
            while (dr.Read())
            {
                RecordCount = RecordCount + 1;
            }
            CloneConn();
            return RecordCount;
        }
    }
}   

Program 里：

 internal static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        private static void Main()
        {
            bool ret;
            Mutex mutex = new Mutex(true, Application.ProductName, out ret);

            if (ret)
            {
                try
                {
                    Application.EnableVisualStyles();
                    Application.SetCompatibleTextRenderingDefault(false);

                    Form_login fl = new Form_login();

                    if (fl.ShowDialog() == DialogResult.OK)
                    {
                        Application.Run(new Main());
                    }
                    mutex.ReleaseMutex();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(null, ex.ToString(), Application.ProductName,
                                       MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    Application.Exit();
                }
            }
            Application.EnableVisualStyles();
        }
    }