I need clarification of the changes that affect the names of cities in time.
I copied the contents of the text files (taken from page: http://download.geonames.org/export/dump/) on excel.
If changes are made to the text file in the previous link, I will need to know where the changes have taken place and what kind of changes have been made.
I noticed that every city name (future class a) matches a precise id. I would like to see if id is unique for every city name, because I thought if it is so, there may be these types of changes:
1) The name of a country can change over time: the id remains the same;
2) A new city is created: a new id is created in the list;
3) The name of a city is deleted: id is deleted from the list
In these cases, I'll just compare the new file with the old file to see what changes have been made.
In case two cities join or divide how do I understand what previous cities have been affected by the union or division?
I wonder why I need to link excel file city names to a list of stores in each city, and I would like to automatically update the changes to the cities where they are present when I decide to update excel files. I must find the right criterion to avoid mistakes.
Could you give me a hand to understand the system with which the geonames database was created and how to set up the excel file?
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You speak about 'administrative divisions'. They can indeed split, merge or become victim of a large reorganisation. An indication is the adminX code, which usually is the country specific code (in Italy the one coming from istat) for levels adm2 or below. The adm1 code mostly is the code used by the US government. Admin divisions are usually not deleted when they cease to exist. They change the feature code to 'historic'.
Just from the feature and the codes it is difficult to know exactly what happend. We use the polygon (also from istat) to determine for the spot features within the adm3 where they now belong to as the boundaries can also change during splits/mergers and reorgs. It is possible that not the entire municipality makes the same change.