Hi,
Yes, you can use mass actions for that.
You can have a "update the values" action on the product_alias column equal to product.product_code if you want to directly set the product code in the alias.
Or you could also append it with an operation like that: concat( product.product_alias, product.product_code )
I've never tried a concat with a mass action but it should work and if it doesn't, you could actually run the same query directly in your phpmyadmin:
update #__hikashop_product SET product_alias = concat( product_alias, product_code )