A simple data structure for subscribers is
email, name, phone, building.
Building is a
VARCHAR field, however data contained in the field is actually mostly numeric. How can I change the field type to
INT without losing data?
Also, if a subscriber sends a request for newsletter, with name, phone, address in the request, and he need to click on a confirm link for the request, what will happen if before he clicks the link, the data structure is changed? For example, if the phone field is deleted, when I insert the new subscribers data, there will be problem because the database structure no longer matches. How can I fix this?