Schema Translation - Information Systems Reengineering, Integration and Normalization - page 102

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Substep 2—Map each PR 1 into an entity.
For each Type 1 primary relation (PR 1 ), define a corresponding entity type and
identify it by the primary key. Its NKAs map to the attributes of the entity type with
the corresponding domains. For example, the PR 1 relational types in the classifica-
tion table can be mapped to the following entities in Fig. 3.27 .
Substep 3—Map each PR 2 into a weak entity.
For each Type 2 primary relation (PR 2 ), define a weak entity with its primary key
being the key of the PR 2 relation. The entity on which it is ID-dependent will be that
entity identified by the primary key on which the PR 2 primary key is dependent. De-
fine a relationship between the owner and the weak entities. All NKA type attributes
of the PR 2 relation will be attributes of the weak entity defined. For example, the
PR 2 relational type in the classification table can be mapped to the following entities
and their relationships in Fig. 3.28 .
Substep 4—Map SR 1 into a binary/n-ary relationship.
For each SR 1 secondary relation, identify the relationship by the primary key of
the SR 1 relation. Define the NKA type attributes as the attributes of the relation-
ship type. If the key of the SR 1 relationship is part of the primary key of another
secondary relation, then it is mapped as an n-ary relationship in the EER model. For

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Fig. 3.27 Map primary relations to entities