private void invoiceDateComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            ///Disable other drop down menu's if this is selected
            if (invoiceDateComboBox.IsEnabled)
            {
                invoiceIDComboBox.IsEnabled     = false;
                invoiceAmountComboBox.IsEnabled = false;
            }
            ///The two other drop down menu's will be disabled when this is being used

            ///When selected, this combo box will show a drop down list with invoice Dates
            ///The user will be able to highlight/select a date and it will be recieved
            ///by the dataGrid1 to show that specific invoice only
            ///
            Console.Write("textbox Value: " + invoiceDateComboBox.SelectedItem);

            //get query needed find invoice
            String sQuery = mydb.SelectInvoiceDate(invoiceDateComboBox.SelectedItem.ToString());

            //datatable used to fget table data.
            dt = db.FillSqlDataTable(sQuery);

            //fill the datagrid
            invoiceGrid1.ItemsSource = dt.DefaultView;
        }