private void BtnCreateCustomer_Click(object sender, RoutedEventArgs e)
        {
            //Open the UserList window after Creating/Updating a user.
            Window srcUserlist = null;
            bool   result      = false;

            if (rbtnYes.IsChecked == true)
            {
                isAdministrator = 1;
            }
            //Store all textbox data into a User object.
            //Check weather this is a NEW user or to UPDATE user.
            if (BtnCreateCustomer.Content.ToString() == "Update Customer")
            {
                if (!string.IsNullOrEmpty(txtUsername.Text))
                {
                    result = true;
                }
                else
                {
                    MessageBox.Show("Username cannot be empty", "Invalid username");
                }
                if (!string.IsNullOrEmpty(txtPassword.Text))
                {
                    result = true;
                }
                else
                {
                    MessageBox.Show("Password cannot be empty", "Invalid Password");
                }

                if (result)
                {
                    try
                    {
                        date = user.UserCreatedDate;
                        user = new User(Convert.ToInt32(txtUserID.Text), txtUsername.Text, txtPassword.Text,
                                        Convert.ToBoolean(isAdministrator), date, false);
                        //Update selected user
                        UsersDB.UpdateCurrentUser(user);

                        srcUserlist = new UserList();
                        srcUserlist.Show();
                        Close();
                    }
                    catch (Exception ex) { MessageBox.Show(ex.Message.ToString()); }
                }
            }
            else
            {
                if (!string.IsNullOrEmpty(txtUsername.Text))
                {
                    result = true;
                }
                else
                {
                    MessageBox.Show("Username cannot be empty", "Invalid username");
                }
                if (!string.IsNullOrEmpty(txtPassword.Text))
                {
                    result = true;
                }
                else
                {
                    MessageBox.Show("Password cannot be empty", "Invalid Password");
                }

                if (result)
                {
                    try
                    {
                        date = DateTime.Now;
                        user = new User(txtUsername.Text, txtPassword.Text, Convert.ToBoolean(isAdministrator), date, false);
                        //Create new user
                        UsersDB.CreateNewUser(user);

                        srcUserlist = new UserList();
                        srcUserlist.Show();
                        this.Close();
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show(ex.Message.ToString());
                    }
                }
            }
        }