private void btnLogin_Click(object sender, EventArgs e)
        {
            //send txt username and pw to getuserlogin function
            var username = txtBox_Username.Text.Trim();
            var password = txtBox_Password.Text.Trim();

            DSLogin.KorisniksDataTable dtLogin = new DSLogin.KorisniksDataTable();
            dtLogin.Clear();


            DALogin.getKorisnikByUsernameAndPassword(dtLogin, username, password);


            if (dtLogin.Rows.Count == 1)
            {
                FrmDashboard formDashboard = new FrmDashboard();
                this.Hide();
                formDashboard.Show();
            }
            else
            {
                MessageBox.Show("Check your username and password");
            }
        }