Boyce-Codd Normal Form

Boyce-Codd Normal Form (BCNF) defines a relation such that all non-trivial functional dependencies are key constraints.

If a relation R is in BCNF, then every field of every tuple holds information that cannot be inferred using functional dependencies alone.

A relational schema R is in Boyce-Codd Normal Form if and only if for every one of its dependencies $$X \rightarrow Y$$, at least one of the following conditions hold:
 * $$X \rightarrow Y$$ is a trivial functional dependency
 * $$X$$ is a superkey for schema R

Lossness
Relations decomposed into BCNF are guaranteed to have lossness join

Dependency Preserving
Relations decomposed into BCNF are not generally guaranteed to be dependency preserving