Sign-in

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Configuration;
using System.Data;

namespace WebApplication1
{
    public partial class SignIn : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }


        protected void Button1_Click(object sender, EventArgs e)
        {
            String CS = ConfigurationManager.ConnectionStrings["MyDatabaseConnectionString1"].ConnectionString;
            using (SqlConnection con = new SqlConnection(CS)) {
                SqlCommand cmd= new SqlCommand("select * from Users where Username='"+ Username.Text+"' and Password='"+Password.Text+"'" , con);
                con.Open();
                SqlDataAdapter sda = new SqlDataAdapter(cmd);
                DataTable dt = new DataTable();
                sda.Fill(dt);
                if (dt.Rows.Count != 0)
                {
                    Session["USERNAME "] = Username.Text;
                    Response.Redirect("~/UserHome.aspx"); }
                else {
                    lblError.Text = "Invalid Username or Password !";

                }


            }
    }


        }
    }