Hi Bob,
Just wanted to share with you a few things that I checked on and some additional information regarding the model I have provided as exampleonly here.
The first address you provided as example does not come up as valid in mapping applications: Mapquest or MS Streets And Trips. However, change the 'W' to 'S' and the address comes up.
Now, in Mapquest the address is shown as: 15210 Tukwila International Blvd,Tukwila,WA 98188-2246
In MS Streets And Trips the address is shown as: 15210 Pacific HWY S, Seattle, WA 98188
The second address you provided as example also gives different results depending on the application:
In Mapquest:
3120 S 176th St,Seatac,WA 98188-4006
In MS Streets And Trips:
3120 S 176th St,Seattle,WA 98188
In referencing this information from the US Postal Service the following was provided:
Actual City name in98188
SEATTLE , WA
Acceptable City names in98188
SEATAC, WA
TUKWILA, WA
Not Acceptable
DUWAMISH, WA
MCMICKEN HEIGHTS, WA
RIVERTON, WA
For others reading this, in regard to the model which I provided, a simple change would be necessary to provide an arbitrary ID as the Primary Key for the Zip Code and City. A Zip Code
can then reference more than one City. If the user were to use a combo box to lookup City and State by Zip, they would simply include the Zip with City name as the reference. In this case I might create another table for Zip Codes alone to ensure referencial
integrity.
ZipCodes
| Column/Field Name |
Data Type |
Definition |
| ZipCode |
Text (PK) |
Primary Key; Unique ZIPs |
ZIPCities
| Column/Field Name |
Data Type |
Definition |
| ZipCityID |
AutoNumber (PK) |
Primary Key; a unique postal code |
| ZipCity_FK_ZipCode |
Text |
Foreign Key; Reference to the parent ZIP |
| ZipCity_FK_CityID |
Text |
Foreign Key; Reference to the parent City |
So in final thought I'd say that depending on who you ask, Zip Codes may or may not cross City boundaries. Once again, the Postal service accepts
the major City, in this case being Seattle, as the correct City related to the Zip Code.