Country, city, state, Post code table design

问题

I have a database in which there is Country, city , states , postcodes in one table with huge set of records. I want to normalize the database structure to avoid redundancy and remove any data duplication. Should I split database and make separate tables for Country, City, state and postcode?

Or merge country , city , state, postcode in Address table?

回答1:

The following tables could be used for addresses in North America. Counties (which would also contain Parishes and other similar geographical subdivisions) is US-centric.

In the addresses table I allow the city_id and county_id to be NULL because, based on HLGEM's comment, you can be in a city OR a county but not both in the state of Virginia. The application code would need to enforce the rule that at least one of these fields is not NULL.

addresses
    id              unsigned int(P)
    street          varchar(50)
    extended        varchar(50) // Default NULL
    city_id         unsigned int(F cities.id) Default NULL
    county_id       unsigned int(F counties.id) Default NULL
    zip             varchar(6) // Will handle all north American zips
    zip4            char(4) // Default NULL
    lat             decimal(10,8) // Allows for ~1mm accuracy at equator. Default NULL
    lon             decimal(11,8) // Allows for ~1mm accuracy at equator. Default NULL

cities
    id                  unsigned int(P)
    state_id            unsigned int(F states.id)
    name                varchar(45)
    fips                unsigned int // Default NULL
    census_code         unsigned int // Default NULL
    census_class_code   char(2) // Default NULL
    gsa_code            unsigned int // Default NULL
    opm_code            unsigned int // Default NULL

city_id and county_id form the Primary key and are foreign keys to their respective tables.

cities_counties
    city_id             unsigned int(F cities.id) ---\_(P)
    county_id           unsigned int(F counties.id)--/

counties
    id                  unsigned int(P)
    state_id            unsigned int(F states.id)
    name                varchar(50)
    fips                unsigned int // Default NULL

See http://en.wikipedia.org/wiki/ISO_3166-1

countries
    id                  char(2)(P)
    iso3                char(3)(U)
    iso_num             char(3)(U)
    name                varchar(44)(U)

See FIPS state codes, FIPS region codes and ISO 3166-2.

states
    id                  unsigned int(P)
    country_id          char(2)(F countries.id)
    code                varchar(3)(I)
    name                varchar(45)
    fips                unsigned int // Default NULL

来源：https://stackoverflow.com/questions/21015175/country-city-state-post-code-table-design

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