find duplicate addresses in database, stop users entering them early?

Question

How do I find duplicate addresses in a database, or better stop people already when filling in the form ? I guess the earlier the better?

Is there any good way of abstra

Answer 1

To add an answer to my own question:

A different way of doing it is ask users for their mobile phone number, send them a text msg for verification. This stops most people messing with duplicate addresses.

I'm talking from personal experience. (thanks pigsback !) They introduced confirmation through mobile phone. That stopped me having 2 accounts! :-)