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

In the USA, you can use USPS Address Standardization Web Tool. It verifies and normalizes addresses for you. This way, you can normalize the address before checking if it already exists in the database. If all the addresses in the database are already normalized, you'll be able to spot duplicates easily.

Sample URL:

https://production.shippingapis.com/ShippingAPI.dll?API=Verify&XML=insert_request_XML_here

Sample request:

  true
  true
  
  
       
       
    205 bagwell ave   
    nutter fort   
    wv   
       
     
  
      

Sample response:

  

    205 BAGWELL AVE
    NUTTER FORT
    WV
    26301
    4322
    05
    C025
  

Other countries might have their own APIs. Other people mentioned 3rd party APIs that support multiple countries that might be useful in some cases.