รบกวนช่วย อธิบาย Code C# เกี่ยวกับระบบ Login นี้ให้หน่อยครับ ว่ามันทำงานอย่างไร

string Utype;
                Utype = dt.Rows[0][5].ToString().Trim();

                if(Utype=="U")
                {
                    Session["USERNAME"] = UserName.Text;
                    Response.Redirect("~/UserHome.aspx");
                }
                if (Utype == "A")
                {
                    Session["USERNAME"] = UserName.Text;
                    Response.Redirect("~/AdminHome.aspx");
                }

 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)
            {
                if (CheckBox1.Checked)
                {
                    Response.Cookies["UNAME"].Value = UserName.Text;
                    Response.Cookies["PWD"].Value = Password.Text;

                    Response.Cookies["UNAME"].Expires = DateTime.Now.AddDays(15);
                    Response.Cookies["PWD"].Expires = DateTime.Now.AddDays(15);
                }
                else
                {
                    Response.Cookies["UNAME"].Expires = DateTime.Now.AddDays(-1);
                    Response.Cookies["PWD"].Expires = DateTime.Now.AddDays(-1);
                }
                string Utype;
                Utype = dt.Rows[0][5].ToString().Trim();

                if(Utype=="U")
                {
                    Session["USERNAME"] = UserName.Text;
                    Response.Redirect("~/UserHome.aspx");
                }
                if (Utype == "A")
                {
                    Session["USERNAME"] = UserName.Text;
                    Response.Redirect("~/AdminHome.aspx");
                }


            }
            else
            {
                lblError.Text = "Invalid Username or Password !";
            }
        }
    }
}