Database Reference
In-Depth Information
preservers, and equipment in the cabin (dishes, silverware, cooking utensils, bedding, and
so on), is not physically attached to the boat. SJSBC provides consumable supplies, such as
charts, navigation topics, tide and current tables, soap, dish towels, toilet paper, and similar
items. The consumable supplies are treated as equipment by SJSBC for tracking and account-
ing purposes.
Keeping track of equipment is an important part of SJSBC's responsibilities. Much of the
equipment is expensive, and those items not physically attached to the boat can be easily dam-
aged, lost, or stolen. SJSBC holds the customer responsible for all of the boat's equipment dur-
ing the period of the charter.
SJSBC likes to keep accurate records of its customers and charters, and customers are
required to keep a log during each charter. Some itineraries and weather conditions are more
dangerous than others, and the data from these logs provide information about the customer
experience. This information is useful for marketing purposes, as well as for evaluating a cus-
tomer's ability to handle a particular boat and itinerary.
Sailboats need maintenance. Note that two definitions of boat are (1) “break out an-
other thousand” and (2) “a hole in the water into which one pours money.” SJSBC is required
by its contracts with the boat owners to keep accurate records of all maintenance activities
and costs.
A data model of a proposed database to support an information system for SJSBC is
shown in Figure 6-42. Note that, because the OWNER entity allows for owners to be companies
are well as individuals, SJSBC can be included as an equipment owner (note that the cardinali-
ties in the diagram allow SJSBC to own equipment while not owning any boats). Also note that
Figure 6-42
Data Model for San Juan
Sailboat Charters
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