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2 Journal of Applied Computer Science

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New definitions of relational operations for nested relations

100%

Krzemiński P. , Myszkorowski K.

tom Vol. 6, nr 1

5-24

In this paper, extended projection and join operators for nested relations will be defined. Such relations arise by rejection of the first normal form as a standard valid for flat relations. They are characterised by occurrence of both attributes with atomic domains and complex attributes whose value is a certain subrelation. The described operators are an extension of projection and join operators of nested relations belonging to algebra as proposed in [10]. They will be defined for a wider class of relations, and they will permit to handle the nested schemas more freely. Both the operators will also act inside the relation class in their partitioned normal form.

Object-oriented database design for a hospital based on nested relations

63%

Kącki E. , Myszkorowski K.

tom Vol. 10, nr 2

49-65

The paper deals with applying object-oriented methodology for modeling a database of a hospital. The presented model is very general, includes all domains of hospital activity and can be extended according to the needs. The semantics of update operations is defined such that the model-inherent integrity constraints such as typing, class membership, subtype- and subclass- relationship, and class predicates can be maintained automatically.