Multiple customer groups per customer

问题:

Is it possible to put customers in multiple customer groups in Magento?

e.g. Customer "Dupant," in groups "Wholesale" & "Retailer."

回答1:

There is similar question on SO here: assign customer to multiple customer groups to magento.

However, I'm not sure if the answer provided is universal because the following snippet

$customer->getGroupId()

is used quite a lot in Magento core, where it is also supposed that group ID returned from this method is integer and not a string (comma separated list of IDs).