The main geoname table from geonames.org has the following fields :
geonameid : integer id of record in geonames database
name : name of geographical point (utf8) varchar(200)
asciiname : name of geographical point in plain ascii characters, varchar(200)
alternatenames : alternatenames, comma separated varchar(5000)
latitude : latitude in decimal degrees (wgs84)
longitude : longitude in decimal degrees (wgs84)
feature class : see http://www.geonames.org/export/codes.html, char(1)
feature code : see http://www.geonames.org/export/codes.html, varchar(10)
country code : ISO-3166 2-letter country code, 2 characters
cc2 : alternate country codes, comma separated, ISO-3166 2-letter country code, 60 characters
admin1 code : fipscode (subject to change to iso code), see exceptions below, see file admin1Codes.txt for display
names of this code; varchar(20)
admin2 code : code for the second administrative division, a county in the US, see file admin2Codes.txt; varchar(80)
admin3 code : code for third level administrative division, varchar(20)
admin4 code : code for fourth level administrative division, varchar(20)
population : bigint (8 byte int)
elevation : in meters, integer
dem : digital elevation model, srtm3 or gtopo30, average elevation of 3''x3'' (ca 90mx90m) or 30''x30''
(ca 900mx900m) area in meters, integer. srtm processed by cgiar/ciat.
timezone : the timezone id (see file timeZone.txt) varchar(40)
modification date : date of last modification in yyyy-MM-dd format