private void SignIn_useEmailToLogin()
        {
            if (txtEmail.Text == "")
            {
                MessageBox.Show("Email field can not be empty.");
                return;
            }

            if (!FormatChecking.Password(txtPassword.Text))
            {
                return;
            }


            if (!DataBaseControl.MatchingEmail_OfAllTable(txtEmail.Text))
            {
                MessageBox.Show("Email does not exist");
                return;
            }

            user = LoginByEmailAndPassword(txtEmail.Text, txtPassword.Text);

            if (user == User.Quit)
            {
                MessageBox.Show("Email or Password is wrong.");
                return;
            }

            userEmail = txtEmail.Text;

            Close();
        }
        private void SignUp()
        {
            if (txtUserAccountName.Text == "")
            {
                MessageBox.Show("User Account Name should not be empty.");
                return;
            }

            if (txtPassword.Text == "")
            {
                MessageBox.Show("User Account Name should not be empty.");
                return;
            }

            bool anyError = false;

            if (!FormatChecking.UserName(txtUserAccountName.Text))
            {
                anyError = true;
            }
            if (!FormatChecking.Password(txtPassword.Text))
            {
                anyError = true;
            }

            if (anyError)
            {
                CleanUpTextBox();
                return;
            }

            if (DataBaseControl.MatchingAccountName_OfAllTable(txtUserAccountName.Text))
            {
                MessageBox.Show("Sorry, the User Account Name has been used.");
                return;
            }

            if (txtEmail.Text != "" && PlayerDataBaseControl.MatchingEmail(txtEmail.Text))
            {
                MessageBox.Show("Sorry, the Email has been used.");
                return;
            }



            PlayerDataBaseControl.Insert(txtUserAccountName.Text,
                                         txtPassword.Text,
                                         txtEmail.Text);


            userAccountName = txtUserAccountName.Text;
            userEmail       = txtEmail.Text;

            PlayerDataBaseControl.playerAccountName = userAccountName;
            PlayerDataBaseControl.Load_PlayerID_By_PlayerAccountName();

            user = User.Player;
            Close();
        }
        private void SignIn_useUserNameToLogin()
        {
            bool anyError = false;

            if (!FormatChecking.UserName(txtUserAccountName.Text))
            {
                anyError = true;
            }
            if (!FormatChecking.Password(txtPassword.Text))
            {
                anyError = true;
            }
            if (anyError)
            {
                return;
            }

            if (!DataBaseControl.MatchingAccountName_OfAllTable(txtUserAccountName.Text))
            {
                MessageBox.Show("User Account Name does not exist.");
                return;
            }

            user = LoginByAccountNameAndPassword(txtUserAccountName.Text, txtPassword.Text);

            if (user == User.Quit)
            {
                MessageBox.Show("User Account Name or Password is wrong.");
                return;
            }

            userAccountName = txtUserAccountName.Text;
            userEmail       = txtEmail.Text;

            Close();
        }