ALTER
发表于 2025-3-23 09:56:01
Nested relations and recursive queries,ucture of a non first normal form relation. It is shown by examples that this method can be used to formulate queries which are rather cumbersome if only flat relations are used. Especially, in some cases the problem of performing a selection on a recursively defined relation disappears. This questi
健谈的人
发表于 2025-3-23 17:18:49
Conference proceedings 1989ch are incorporating features of models involving complex objects. A variety of approaches is represented in this volume. The first three papers give overviews of major pioneering implementation efforts. The fourth paper is devoted to the important issue of implementation of storage structures. The
Irrigate
发表于 2025-3-23 19:59:23
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Confound
发表于 2025-3-23 22:55:47
Query languages for Nested Relational Databases,ussed and compared, SQL/NF, and Heidelberg Data Base Language (HDBL). Two extensions of these languages are considered. X-SQL/NF is a role-join extended version of SQL/NF that incorporates an ISA hierarchy into the semantics of the language. A recursive version of HDBL allows the definition of a transitive closure operation on nested relations.
杀死
发表于 2025-3-24 04:41:25
An approach to manage large inheritance networks within a DBS supporting nested relations,ortance is the handling of the general graph structure provided by KL-ONE like formalisms within the tree structure offered by nested relations. The described approach is oriented towards the specific requirements which have to be met in a natural language processing environment.
MITE
发表于 2025-3-24 07:52:23
On the normalization in Nested Relational Databases,are structured with respect to a nonredundant set of data dependencies. The semantic differences between functional and multivalued dependencies are distinguished and incorporated in the design method. The properties of the nested normal form, and the other design methods for the nested normal form are also discussed.
Gustatory
发表于 2025-3-24 11:12:43
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acrimony
发表于 2025-3-24 18:22:41
,Four views of complex objects: A sophisticate’s introduction,modeling paradigms are: complex object types (including nested relations); semantic models; complex object models using object identifiers; and the model of the conceptual language Galileo. The presentation is largely informal, with a focus on philosophic issues.
abduction
发表于 2025-3-24 21:14:45
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木讷
发表于 2025-3-25 01:29:14
On the uniqueness of nested relations, than K tuples is NP-complete. A template dependency is given as an essential integrity constraint to guarantee that a class of first normal form relations has unique nested relations with minimum number of tuples.