Question

I want to save a geographical data in a relational db and be able to query for data based on their location (country, state or similar not coordinates).

My current solution is to have 4 extra fields (all countries I’m interested in have 2 or 3 administrative divisions) in my table and filter on strings. But I realize that this is a bad solution and would like to normalize my table.

I will also use that data to determine which page my users wants to visit, so it must be simple to lookup a request like “/usa/california/san_fransisco/…”

The only other solution I can come up with is to store those 4 extra fields in another table and link them with a foreign key but that would still mean some data duplication as country name would duplicated in allot of rows.

Is there any better way of doing this?

Answer 1

Normalizing is definitely the way to go. Databases are designed to function that way. Yes the query might look long but it’s not that bad. It might look something like this:

select * --or whatever fields you need
  from Customer
       left outer join City    on (Customers.CityID = City.CityID)
       left outer join State   on (City.StateID     = State.StateID)
       left outer join Country on (State.CountryID  = Country.CountryID)
 where CustomerID = 1234