HEDGE
发表于 2025-3-23 13:01:58
Achievements of relational database schema design theory revisited,ema design aims at both faithful formalization of the application and optimization at design time. It is guided by four heuristics: Separation of Aspects, Separation of Specializations, Inferential Completeness and Unique Flavor. A theory of schema design is to investigate these heuristics and to pr
Chivalrous
发表于 2025-3-23 17:10:36
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小步舞
发表于 2025-3-23 20:34:58
The evolving algebra semantics of class and role hierarchies,bras provide an elegant way to specify the operational semantics of object-oriented data models. In particular, we define the formal semantics of a novice feature of object-oriented data models proposed recently by different authors: role hierarchies. As opposed to traditional class hierarchies, rol
arthroplasty
发表于 2025-3-24 02:04:06
Semantics in spatial databases,model is particularly suited to model spatial database applications in which exact geometrical information is required and in which this information can be approximated by linear geometrical spatial objects. The topological model on the other hand is suitable for applications in which rather than ex
小木槌
发表于 2025-3-24 03:07:08
The additivity problem for data dependencies in incomplete relational databases,tabases. We introduce null functional dependencies (NFDs) and null inclusion dependencies (NINDs) to cater for the situation when a database is incomplete and thus contains null values. If a NFD or NIND is weakly satisfied in a database, then there exists a possible world of this database in which t
领带
发表于 2025-3-24 09:17:12
A semantics-based approach to design of query languages for partial information,y in the presence of nulls. In this paper a different point of view is advocated. We believe that the semantics of partiality must be clearly understood and it should give us new design principles for languages for databases with partial information..There are different sources of partial informatio
贪婪地吃
发表于 2025-3-24 13:09:59
Constraint databases: A survey,nt databases: known results, remaining open problems and current research directions. The paper also describes a new algebra for databases with integer order constraints and a complexity analysis of evaluating queries in this algebra.
MUTE
发表于 2025-3-24 17:37:23
Redundancy elimination and a new normal form for relational database design,ain functional dependencies (FDs) and arbitrary join dependencies (JDs). Extending previous work on the relationship between fourth normal form (4NF) and redundancy elimination, a general definition of redundancy is proposed which is applicable to any type of relational dependency including arbitrar
共同确定为确
发表于 2025-3-24 22:16:14
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Ventilator
发表于 2025-3-24 23:56:45
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