private void LoginButton_Click(object sender, EventArgs e) { if (LookUpUser(UsernameBox.Text, PasswordBox.Text) != 0) { this.Hide(); MainScreen mainScreen = new MainScreen(); mainScreen.login = this; InfoLog.userLoginLog(Data.getUserId()); mainScreen.Show(); } else { MessageBox.Show(ErrorMessage); PasswordBox.Text = ""; } }