Is 2NF a Stable Normal Form?
| Autor: | Sapir, Amir, Sapir, Ariel |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | Traditionally, it was accepted that a relational database can be normalized step-by-step, from a set of un-normalized tables to tables in $1NF$, then to $2NF$, then to $3NF$, then (possibly) to $BCNF$. The rule applied to a table in $1NF$ in order to transform it to a set of tables in $2NF$ seems to be too straightforward to pose any difficulty. However, we show that, depending on the set of functional dependencies, it is impossible to reach $2NF$ and stop there; one must, in these cases, perform the normalization from $1NF$ to $3NF$ as an indecomposable move. The minimal setup to exhibit the phenomena requires a single composite key, and two partially overlapping chains of transitive dependencies. Comment: 10 pages, 1 figure |
| Databáze: | arXiv |
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