currently, I am developing a Magento extension, that needs to add several custom attributes to the customer address. I've found several tutorials on the topic that describe precisely what I need to build http://www.unexpectedit.com/magento/add-new-customer-attribute-onepage-magento-checkout http://www.excellencemagentoblog.com/magento-adding-custom-field-to-customer-address
They all use ALTER TABLE to add columns to several DB tables. My question is :
Is it upgrade safely to do this?
Thanks in advance