Titlebook: Dependencies in Relational Databases; Bernhard Thalheim Textbook 1991 Springer Fachmedien Wiesbaden 1991 Datenbank.relationale Datenbank

古文字學(xué)

創(chuàng)造性

Database Schemes and Databases, the theory of abstract data types /REI 84/ and especially the approach of /PDGG 88/, /VOSS 87/ and /DEAB 85/. The underlying concept used in the relational model is the same as that used to define a mathematical relation (in set theory and algebra). Simply, a relation is a subset of the Cartesian p

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Painstaking

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Inclusion Dependencies,whether they are designed properly. Much less is known about how the relations should fit together. In general, an inclusion dependency (IND) is of the form.where R and S are predicates (or relation scheme names), and the A.’s and B.’s are attributes of the corresponding schemes. The inclusion depen

ANTIC

Dependencies in Relations with Null Values and Incomplete Informations,m of querying these so-called incomplete databases. In any real-world database, there will be entries having values that are “special”, in the sense that they are not drawn from the value set for that entry. Some of such special values are of the meaning “value unknown”, “item inapplicable”, “value

壁畫

Horizontal Decomposition Dependencies,troduction in /CODD 72/. The use of vertical decompositions always requires some constraints to be satisfied, for instance a join dependency or a functional dependency, in order to be able to regain the original relation by taking the join of its projections. In /ARDE 80/, /THAL 84/ and AABM 80/ the

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The Relationship between Dependency Classes, papers on dependency theory are given. By some authors it was noticed that dependency theory is in a chaotic state. This book should be understood as an attempt to present the most important results on dependency theory. The usefulness of such a great number of different constraints is an open prob

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