Some Concepts That Underpin GIS - Introducing Geographic Information Systems with ArcGIS - page 28

Here, mainly for purposes of illustration, the MASTER table is miniscule, consisting only of a license
plate number and an owner identification. The key field, shown in bold font, consists of a unique
character string (no two license plates are the same) and an owner identification number. The contents of
this second column may not be unique, since one person my own several vehicles.

TABLE 1-1

MASTER

Plate_# Owner_ID

OWNER

Owner_ID Name Address SSN

VEHICLE

Plate_# Color Model Year Type_code VIN

VEH_TYPE

Type_Code Weight Length Width H_Power Fuel_Cnsup

VOTERS

SSN Name Precinct_Code Regis_Party

PRECINCT

Prec_Name Location Supervisor Precinct_Code

ARRESTED

Name Alias SSN Offense Convicted Court_Doc_#

ACCOUNTING

Plate_# Date_Paid Insurance_Co_Code

INSURERS

Insurance_Co_Code Co_Name Location Phone

Both fields in MASTER refer to—link to—the other eight tables, either directly or indirectly. Plate_#
allows the user access to both VEHICLE and ACCOUNTING.

The VEHICLE table describes some of the attributes of the car or truck in question. Since some aspects of
all vehicles of a certain year, model, and manufacturer are identical, it would be a waste of space and an
updating nightmare to place this information in a record describing a particular vehicle. So each record
carries a Type_Code that refers to a key field in the table VEH_TYPE. There you will find the vehicle
weight, length, width, horsepower, and fuel consumption data.

The ACCOUNTING table indicates whether taxes and registration have been paid. Also, here is a
reference to the INSURERS table, which carries information about the companies that insure vehicles in
the state.

The other column in the MASTER table contains an Owner_ID code that matches up with the key in the
table OWNER. That table could contain a host of information about the owner of the vehicle. Shown
in the table are names and addresses. Also there is the owner's Social Security number (SSN). Perhaps
there is a “motor-voter” effort to register all vehicle owners. With the SSN, which is the key field in the
VOTERS table, a user could determine which owners were already registered to vote. Further, with the
Precinct_Code, information about the location of the voting precinct could be obtained.