private void button1_Click(object sender, EventArgs e)
    {
        try
        {
            ProjectFunc loginF = new ProjectFunc();
            loginF.GetId(username, password);

            if(loginF.Userid == 0)
            {
                MessageBox.Show("Wrong username and/or password, try again.");
            }

            else
            {
                this.Hide();
            }
            username_txt.Clear();
            password_txt.Clear();

        catch (Exception ex)
        {
            MessageBox.Show("Could not connect to DB" + ex);
        }

public void GetId(string username, string password)
    {
        using (var con = new SqlConnection(myCon))
        {
            con.Open();
            using (var cmd =new SqlCommand("Select userid from Login, UserLogin where Login.loginid   = UserLogin.loginid and username = '" + username + "' and password = '" + password + "' ;", con);
            {
                using (var reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        userId = (int)reader[0];
                        Main menu = new Main();
                        menu.Show();
                    }
                }
            }
        }

    }

private void button1_Click(object sender, EventArgs e)
    {
    } // 5 buttons totally, nothing else so far.