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Erschienen in:
2011 | OriginalPaper | Buchkapitel
A Uniform Framework for Temporal Functional Dependencies with Multiple Granularities
verfasst von : Carlo Combi, Angelo Montanari, Pietro Sala
Erschienen in: Advances in Spatial and Temporal Databases
Verlag: Springer Berlin Heidelberg
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Temporal functional dependencies (TFDs) add a temporal component to classical functional dependencies to deal with temporal data. As an example, while functional dependencies model constraints like “
employees with the same role get the same salary
”, TFDs can represent constraints like “
for any given month, employees with the same role get the same salary (but their salary may change from one month to the next one)
” or “
current salaries of employees uniquely depend on their current and previous roles
”. In this paper, we propose a general framework for specifying TFDs, possibly involving different time granularities, and for checking whether or not a given database instance satisfies them. The proposed framework subsumes existing formalisms for TFDs and it allows one to encode TFDs which are not captured by them.