Second, the decomposition process is basically a processof taking projections…
Nonloss is not strictly the same as information equivalent.
Normalisation is done against RELVARs
EQD Equality Dependency
Update anomaly is usually caused by FD
- Insertion anomaly
- Deletion anomaly
- Modification anomaly
In general, BCNF is the solution to the problems caused by the kinds of anomalies listed above.
Higher level of normalisation => more redunancies and fewer update anomalies.
- FD => BCNF
- JD => 5NF
Decomposition adds constraints (multi-RELVAR)
Normal form is equivalent to canonical form of data.