string strQuery = "select count(*) from Registration where  username=@username and password=@password";

    SqlConnection connection = DBConnection.getConnection();
    connection.Open();

    SqlCommand cmd = new SqlCommand();
    cmd.Connection = connection;
    cmd.CommandText = strQuery;

    cmd.Parameters.Add("@username", txt1_username.Text);
    cmd.Parameters.Add("@password", txt2_password.Text);

    int intRowCount = (int) cmd.ExecuteScalar();
    txt1_username.Text = intRowCount.ToString();
    connection.Close();


    if (intRowCount == 1)
    {
        string strquery = "select customer_id from Registration where username=@username";
        SqlConnection connection2 = DBConnection.getConnection();
        connection2.Open();
        SqlCommand cmd2 = new SqlCommand();
        cmd2.Connection = connection;
        cmd2.CommandText = strquery;

        string customerID = cmd2.ExecuteScalar().ToString();
        Session["customerID"] = customerID;
        connection2.Close();

        Session.Add("username", txt1_username.Text);
        Response.Redirect("Succes.aspx");

    }


    else
    {
        Messages myMsg = new Messages(); // ایجاد نمونه از کلاس
        myMsg.CreateMessageAlert("مقادیر ورودی صحیح نمی باشند . مجددا سعی کنید");
        txt1_username.Text = "";
        txt2_password.Text = "";
    }