For some versions of the cart, when you load products in the administrator area of your website (Products & Categories -> Bulk Product Loader), you will have four options for the "Data Update Rule."
Overwrite Existing Data – Add New: This option will update any products already in your shopping cart (assuming you have listed them on your spreadsheet), as well as add any new products listed on your spreadsheet. Products already existing in your shopping cart, but not included on the spreadsheet will not be affected. Any of the following fields, if not included on your spreadsheet, will be set to their default values :
priority='0'
is_visible='Yes'
call_for_price='No'
is_taxable='Yes'
price_level_1='0.00'
price_level_2='0.00'
price_level_3='0.00'
free_shipping='No'
weight='0'
inter_pack='0'
case_pack='0'
min_order='1'
max_order='0'
is_home='Yes'
is_hotdeal='Yes'
digital_product='No'
inventory_control='No'
stock='0'
stock_warning='0'
inventory_rule='Hide'
Keep Existing Data – Add New: This option will update any products already in your shopping cart (assuming you have listed them on your spreadsheet), as well as add any new products listed on your spreadsheet.
Clear Existing – Add New: This option will delete all existing products that are not listed on your spreadsheet. It will update any existing products that are listed on your spreadsheet. Finally, it will add any new products listed.
Update Existing Products Only: This option will not add any new products from your spreadsheet. It will only update existing products.