constitutional 发表于 2025-3-23 09:54:06
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Özgehan Şenyuva,Ramón Llopis-Goig. Codd’s relational algebra is a high-level language in which questions can be put simply and succinctly /CODD 72/. Concepts from relational algebra have been incorporated into the design of several new database query languages, into view conceptions and into the conception of internal database sche软弱 发表于 2025-3-23 19:54:51
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https://doi.org/10.1007/978-3-031-58409-1re, the semantics in relational database schemata. Functional dependence is an important property of a relation. In a relation which verifies some functional dependency, there is a functional connection between the parts of tuples. Functional dependencies can be defined like functions f: X --> Y whiSuggestions 发表于 2025-3-24 04:51:49
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Erchimen Gavriliev,Tatiana Avdeenkom 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严厉批评 发表于 2025-3-24 13:53:32
Erchimen Gavriliev,Tatiana Avdeenkotroduction 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/ theEuthyroid 发表于 2025-3-24 15:21:15
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Dependencies in Relational Databases978-3-663-12018-6Series ISSN 0138-502Xcochlea 发表于 2025-3-24 23:32:21
0138-502X Overview: 978-3-663-12019-3978-3-663-12018-6Series ISSN 0138-502X