Relation $R$ is decomposed using a set of functional dependencies, $F$, and relation $S$ is decomposed using another set of functional dependencies, $G$. One decomposition is definitely $\text{BCNF}$, the other is definitely $3NF$, but it is not known which is which. To make a guaranteed identification, which one of the following tests should be used on the decompositions? (Assume that the closures of $F$ and $G$ are available).
This is because the relation whose highest normal form is 3NF will fail the BCNF test, but both will pass the 3NF test.
Answer -> $C$ ( & Only $C$).
BCNF may or may not preserve dependency preservation. 3NF satisfy dependency preservation. Both BCNF and 3NF are Lossless join decomposition. So we BCNF definition is required.
Answer is C. BCNF definition
Explain please
3NF Dependency always preserved but in BCNF it may or may not be preserved.