ขอโค้ด ล็อกอิน Login Visual C# .NET ใช้ SQL 2008 เป็นฐานข้อมูลค๊า

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;


public partial class LoginControl : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {
        
        if (Session["User"] != null)
        {
            Response.Write("session has valu");
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection(ฐานข้อมูลของคุณ);
        try
        {
            conn.Open();
            string SqlText = "SELECT UserID, Username, Position FROM [User] WHERE Username=@Username AND Password=@Password";
            SqlCommand cmd = new SqlCommand(SqlText, conn);
            cmd.Parameters.AddWithValue("@Username", TextBox1.Text.Trim());
            cmd.Parameters.AddWithValue("@Password", TextBox2.Text.Trim());
            SqlDataReader dr = cmd.ExecuteReader();
            try
            {
                if (dr != null && dr.HasRows == true)
                {
                   // Response.Write("login true");

                    if (dr.Read())
                    {
                        Session["User"] = dr["Username"].ToString();
                        Session["UserID"] = dr["UserID"].ToString();
                        Session["Position"] = dr["Position"].ToString();
                        Session.Timeout = 10;
                    }
                    dr.Close();
                }
                else
                {
                    Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "CallJs", "alert('Password ไม่ถูกต้องกรูณา Login ใหม่อีกครั้ง');", true);
                }
            }
            finally
            {
                conn.Close();
            }
        }
        catch (Exception ex)
        {
            Response.Write(ex.ToString());
        }
    }
}

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

namespace MSEquipment
{
    public partial class frmLogin : Form
    {
        public frmLogin()
        {
            InitializeComponent();
        }

        SqlConnection Conn = new SqlConnection();

        private void frmLogin_Load(object sender, EventArgs e)
        {
            string strConn = DBConnString.strConn;

            if (Conn.State == ConnectionState.Open)
            {
                Conn.Close();
            }
            Conn.ConnectionString = strConn;
            Conn.Open();
        }

        private void cmdLogin_Click(object sender, EventArgs e)
        {
            StringBuilder sb = new StringBuilder();

            sb.Append("SELECT UserName,Password FROM MEMBER");
            sb.Append(" WHERE (UserName=@UserName)");
            sb.Append(" AND (Password=@Password)");

            SqlParameter UserName = new SqlParameter("UserName", SqlDbType.VarChar);
            SqlParameter Password = new SqlParameter("Password", SqlDbType.VarChar);

            string sqlLogin;
            sqlLogin = sb.ToString();

            SqlCommand com = new SqlCommand();
            SqlDataReader dr;

            com.CommandType = CommandType.Text;
            com.CommandText = sqlLogin;
            com.Connection = Conn;
            com.Parameters.Add(UserName).Value = txtUserName.Text;
            com.Parameters.Add(Password).Value = txtPassword.Text;

            dr = com.ExecuteReader();
            if (dr.HasRows)
            {
                frmMain frm = new frmMain();
                frm.Show();
                this.Hide();
            }
            else
            {
                MessageBox.Show("UserName หรือ Password ที่คุณป้อน ไม่ถูกต้อง !!!", "ผลการทำงาน", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                txtUserName.Text = "";
                txtUserName.Focus();
                txtPassword.Text = "";
            }

            dr.Close();
            dr.Dispose();
        }

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

Console.WriteLine("Visual Studio C# 2010");

textBox1.Text="Text textBox";

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

namespace Hospital
{
    public partial class Login : Form
    {
        public Login()
        {
            InitializeComponent();
        }
        DBHospitalDataContext db = new DBHospitalDataContext();
        private void btnLogin_Click(object sender, EventArgs e)
        {
            if (txtUser.Text.Trim() == "" && txtPassword.Text.Trim() == "")
            {
                MessageBox.Show("กรุณากรอกชื่อผู้ใช้และรหัสผ่าน", "Login ผิดพลาด", MessageBoxButtons.OK, MessageBoxIcon.Error);
                txtUser.Focus();
                return;
            }
            if (chkLogin(txtUser.Text, txtPassword.Text))
            {
                MDIParent1 h = new MDIParent1();
                h.Username = txtUser.Text.Trim();
                h.Show();
                this.Hide();
            }
        }
        private bool chkLogin(string user, string pass)
        {
            try
            {
                var q = from e in db.Employees
                        where e.UserName == txtUser.Text
                        && e.Pass == txtPassword.Text
                        select e;

                if (q.Any())
                {
                    MessageBox.Show("ยินดีต้อนรับเข้าสู่ระบบ", "Login ถูกต้อง", MessageBoxButtons.OK, MessageBoxIcon.Information);

                    return true;
                }
                else
                {
                    MessageBox.Show("ชื่อผู้ใช้หรือรหัสผ่านไม่ถูกต้อง", "Login ผิดพลาด", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    clearForm();
                    return false;
                }
            }
            catch { }

        }
        private void clearForm()
        {
            txtUser.Text = "";
            txtPassword.Text = "";
            txtUser.Focus();
        }