English

Is 2NF a Stable Normal Form?

Databases 2021-07-01 v1

Abstract

Traditionally, it was accepted that a relational database can be normalized step-by-step, from a set of un-normalized tables to tables in 1NF1NF, then to 2NF2NF, then to 3NF3NF, then (possibly) to BCNFBCNF. The rule applied to a table in 1NF1NF in order to transform it to a set of tables in 2NF2NF 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 2NF2NF and stop there; one must, in these cases, perform the normalization from 1NF1NF to 3NF3NF as an indecomposable move. The minimal setup to exhibit the phenomena requires a single composite key, and two partially overlapping chains of transitive dependencies.

Cite

@article{arxiv.2106.15664,
  title  = {Is 2NF a Stable Normal Form?},
  author = {Amir Sapir and Ariel Sapir},
  journal= {arXiv preprint arXiv:2106.15664},
  year   = {2021}
}

Comments

10 pages, 1 figure

R2 v1 2026-06-24T03:44:11.461Z