private void btLogin_Click(object sender, EventArgs e)
        {
            string strConn = "Data Source=localhost;Initial Catalog=login;User Id=test;Password=test;";
            SqlConnection conn = new SqlConnection(strConn);
            if (conn.State== ConnectionState.Open)
	        {
                conn.Close();
	        }
            conn.Open();
            string cmdText = @"select username,password,status from login 
                                where username=@username 
                                and password=@password";
            SqlCommand command = new SqlCommand(cmdText, conn);
            command.Parameters.Add("@username",SqlDbType.NVarChar).Value = textBox1.Text.Trim();
            command.Parameters.Add("@password", SqlDbType.NVarChar).Value = textBox2.Text.Trim();
            SqlDataReader reader = command.ExecuteReader();
            while (reader.Read())
            {
                if (reader["status"].ToString()== "2")
                {
                    // redirect to page เจ้าหน้าที่ 
                }
                else if (reader["status"].ToString() == "3")
                {
                    // redirect to page ผู้บริหาร
                }
                else
                {
                    // redirect to page สมาชิกทั่วไป
                }
            }
            // respone.write("login fail ?");
            reader.Close();
            conn.Close();
        }