/// <summary>
        /// Creator: Cash Carlson
        /// Created: 04/25/2020
        /// Approver: Rasha Mohammed
        ///
        /// When clicked will trigger refresh for viewing all lifetime employee sales data
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnViewEmployeeSales_Click(object sender, RoutedEventArgs e)
        {
            int employeeID;

            // Try to parse textbox into int
            bool success = Int32.TryParse(txtEmployeeID.Text, out employeeID);

            if (success)
            {
                RefreshData(_salesDataManager.RetrieveAllEmployeeSalesData(employeeID));
            }
            else
            {
                // failure message
                MessageBox.Show("Please enter a valid Employee ID");
            }
        }