private void SignIn_Clicked() { //regex pattern check string pattern = @"[A-Z0-9a-z_]+"; if (!Regex.IsMatch(Username.Text, pattern) || !Regex.IsMatch(Password.Password, pattern)) { MessageBox.Show("Incorrect input, check and try again!"); Username.Focus(); return; } CONNECTION.DbHandle = new DataBaseHandler(); //set attributes CONNECTION.DbHandle.Password = Password.Password; CONNECTION.DbHandle.Username = Username.Text; //test //endtest if (CONNECTION.DbHandle.DB_Query_Result()) { UserFrame userFrame = new UserFrame(); userFrame.Show(); this.Close(); } else { MessageBox.Show("The combination of username and password you have entered is incorrect!"); this.reset(); } }