private void createEmployeeButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                String firstName = inputFirstNameBox.Text;
                String lastName  = inputLastNameBox.Text;
                SqlManage.CreateEmployee(nextEmployeeIdNum, firstName, lastName);
                nextEmployeeIdNum++;

                ClearAll();
                outputTextBlock.Text = firstName + " " + lastName + " added.";
            }
            catch (SqlException ex)
            {
                ClearAll();
                outputTextBlock.Text = ex.Message;
            }
            catch (IOException ex)
            {
                ClearAll();
                outputTextBlock.Text = ex.Message;
            }
        }