Page 171 -

156 NGUYEN AND DILLON
Enter judges for events

Judge (name) . . . is assigned to Event ( ) . . .
Constraint: If Judge j is assigned to Event e, and Event e is of EventType t, then Judge
j is (must be) qualified for EventType t.

Note: As mentioned earlier, while identifying fact types, we are in a good position to identify the
constraints applied to the fact types under consideration, and we can then express the constraints
in terms of these fact types. In this section, to save space, we will record only the “less common”
constraints. In particular, we omit “common” constraints such as uniqueness constraints (e.g., each
club must be at one address) or mandatory constraints (e.g., each club must have a phone number). In
practice, these common constraints, due to their importance, are routinely specified on the conceptual
schema diagram, especially when tools such as VisioModeler (see ORM, 2007) are used.

Fact Types About the Team Registrations

Register a team and its members in a meet (for a competition). Similar to the notion that a team
is a club in a competition, we have the concept of a “member” (for want of a better term) as a
gymnast participating in a team. The inclusion of “member” makes it a little clearer to express,
for example, in the case of the awarding of a score, which the gymnast receives as a member of
a team rather than just as a gymnast of a club.

Team ([club] + [Competition]) . . . enter Competition ( ) . . .
Member ([Gymnast] + [Team]) . . . is Gymnast ( ) . . .
Member ( ) . . . belongs to Team ( ) . . .
Constraint (informally expressed): A gymnast (member) can belong to a team, which
is registered for a particular type of competition, only if the gymnast is eligible (hav-
ing suitable gender and age) for that type of competition.

Fact Types About Scoring
The fact types related to scoring are listed below. Note that the last two fact types can be derived
from the first fact type and other relevant fact types that have been identified earlier. For example,
the score received by a gymnast for an event is calculated by discarding the highest and the lowest
scores of the judges.

Enter a score
Judge ( ) . . . gives Score (number) . . . to Member ( ) . . . in Event ( ) . . .
Member ( ) . . . receives Score ( ) . . . for Event ( ) . . . [derived]
Team ( ) . . . receives Score ( ) . . . for Event ( ) . . . [derived]
Constraint (informally expressed): A gymnast participating in a competition must have
a score for each event of that competition from each of the judges of the event.

Conceptual Schema Diagram

From the fact types that have been identified above, we construct the ORM conceptual schema
shown in Figure 9.4.