Database Reference
In-Depth Information
all of the items on both the list of subjects and the Preliminary Table List. Let's take a look
at an example of this process.
Assume that you're developing a database for an equipment rental business, and you're
working with the list of subjects and the Preliminary Table List shown in
Figure 7.3
.
Figure 7.3. The list of subjects and the Preliminary Table List for an equipment rent-
al business
As you review these lists, you discover two duplicate items: “Equipment” and “Rental
Agreements.” Theseitemswarrantfurtherexamination, soyoustartwith“Equipment” and
try to determine whether each occurrence represents a
different
subject. In reviewing your
interview notes, you find that “Equipment” on the list of subjects represents items such as
tools,appliances,andaudiovisualequipment.Thenyourememberthat“Equipment”onthe
Preliminary Table List also includes trucks, vans, and trailers. You review your interview
notes further and discover that vehicle rentals are treated differently from “regular” equip-
mentrentals.Therefore,eachoccurrenceof“Equipment”
does
representadifferentsubject.
You resolve the duplication by keeping one occurrence of “Equipment” and renaming the
other “Vehicles.” You then list both items on the Preliminary Table List.
Nowyougothroughthesameprocesswith“Rental Agreements.” Fortunately,youdiscov-
er that both occurrences share exactly the same meaning. The only thing you have to do in
this case is cross out “Rental Agreements” on the list of subjects. Now you can continue
your review until you've inspected each item on the list of subjects.
Figure 7.4
shows the
revised list of subjects and the Preliminary Table List.
