Named_Place
Description:
Name Null? Type ------------------------------- -------- ---- NAMED_PLACE_ID NOT NULL NUMBER CONTAINING_NAMED_PLACE_ID NUMBER PLACE_NAME VARCHAR2(50) PLACE_TYPE_CODE VARCHAR2(20) POL_LEVEL NUMBER
This table implements a hierarchy of place names in the same way that the taxonomic hierarchy is expressed in the Taxonomic_Relationship table. The recursive relationship (Named_Places are contained within other Named_Places) implies that place names are organized into a hierarchy, a reasonable working model for the existing political organization of countries.
Place_Type_Code was the original attempt to represent the different hierarchical levels in political entities. It began with Continent, Country, State, County, and Town. However, I quickly found that there were many other names for political units at the same relative level, e.g., state: Province, Departamento, Territory, District, County (yes!), Parish, Region, Ward, etc., etc. Further, we run into non-hierarchical situations that, while not extremely common, do mess up the logic of this arrangement. The specific example I have in mind are French Guiana, Guadeloupe, and St. Pierre & Miquelon: all parts of France, but on different continents. The Pol_Level field is intended to handle part of this problem, using a value of 1 for all of the primary political divisions of a country, and so on. (And for the sake of the hierarchy, French Guiana is coded as a country.)
The Named_Place_ID field in Locality connects that table with Named_Place.