On 05/22/2011 09:42 PM, Craig Ringer wrote:
On 23/05/2011 9:11 AM, Andrej wrote:
On 23 May 2011 10:00, Tarlika Elisabeth Schmitz
<postgres...@numerixtechnology.de> wrote:
On Sun, 22 May 2011 21:05:26 +0100
Tarlika Elisabeth Schmitz<postgres...@numerixtechnology.de> wrote:
A column contains location information, which may contain any of the
following:
1) null
2) country name (e.g. "France")
3) city name, region name (e.g. "Bonn, Nordrhein-Westfalen")
4) city name, Rg. region name (e.g. "Frankfurt, Rg. Hessen")
5) city name, Rg region name (e.g. "Frankfurt, Rg Hessen")
I also need to cope with variations of COUNTRY.NAME and REGION.NAME.
That isn't a table structure, that's a freeform text structure. You didn't
state your question, Tarlika, but your database structure is terrible. For
example, "region" and "country" should be different columns. Really!
How you get your raw data into those columns can be interesting.
This is a hard problem. You're dealing with free-form data that might be
easily understood by humans, but relies on various contextual information and
knowledge that makes it really hard for computers to understand.
If you want to do a good job of this, your best bet is to plug in 3rd party
address analysis software that is dedicated to this task. Most (all?) such
These aren't really addresses, as the OP presents them.
packages are commercial, proprietary affairs. They exist because it's really,
really hard to do this right.
Another thing of great import is whether the city can occur in the
data column all by itself; if yes, it's next to impossible to distinguish
it from a country.
Not least because some places are both, eg:
Luxembourg
The Vatican
Singapore
(The Grand Duchy of Luxembourg has other cities, but still serves as an
example).
And,of course, you have to distinguish the City of London from London. New
York City comprises five boroughs (counties), each of which is itself a city.
(Brooklyn is one of the largest cities in the world all by itself.)
"Region" has different meanings in different areas - it can mean part of a
county, or state / province, or nation, or continent. "The Baltic region",
"the Northeast", "upstate", "the North Country", "Europe" are all regions.
The OP should share more about the semantics of their problem domain and
whether they really intend those table structures to be table structures. Really?
--
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg
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