normalization

The algorithms are dependency preserving as the original Client Rental relation can be recreated by joining the 3NF relations [R.

In this paper we have presented algorithms for relational database normalization into 2NF and 3NF using their general definitions in a step-by-step feature.

In [6] it was shown that 3NF has the least amount of redundancy among all dependency preserving normal forms.

R is not in 3NF because of the functional dependency sId, pId [right arrow] delivPlace:

In this case the lack of 3NF is the source of redundancies and update anomalies.

It turns out ([6]) that the best form for relation schema is 3NF, although some redundancies in tables having this form can still remain.

R is in Third Normal Form (3NF) with respect to F (or simply in 3NF whenever F is understood from context) if, for every nontrivial FD, X [right arrow] A [element of] F, either X is a superkey for R or A is prime.

In Jou and Fischer [1982], it was shown that, in general, testing whether R is in 3NF is NP-complete.

Testing whether R is in 3NF with respect to a set of FDs F, which satisfies the intersection property, can be done in polynomial time in the size of F.

Second, if |KEYS(F)| [is greater than] 1, then the result follows, since by Lemma 42 all of the attributes A [element of] sch(R) are prime and if R is in 3NF, then it is also in 2NF.

Should it be sufficient to leave students with the impression that 3NF relations are suitable for business or sufficient for most applications?

3NF A relation in 2NF + all non-key attributes are dependent only on the primary key.

The central part of the article gives the definitions of temporal BCNF (TBCNF) and temporal 3NF (T3NF) and algorithms for achieving TBCNF and T3NF decompositions.

Therefore we give the definition of temporal 3NF (T3NF), and present an algorithm that provides lossless, dependency-preserving, T3NF decomposition.

In the next section, we define the temporal analogue of (nontemporal) 3NF that relaxes, in a restricted way, the conditions of TBCNF to allow certain types of data redundancy in order to preserve TFDs.