Take the 2-minute tour ×
Database Administrators Stack Exchange is a question and answer site for database professionals who wish to improve their database skills and learn from others in the community. It's 100% free, no registration required.

I have a problem understanding a particular case of BCNF. Let's suppose that we have a relation R(B, C, D) with df:{C->D}. Is my relation in BCNF and if yes why??? Is C considered as superkey?

share|improve this question
add comment

1 Answer

The only key is {BC}. You have a partial key dependency: C->D. Since you have a partial key dependency, R is not in 2NF. So R is also not in BCNF.

An informal way of expressing BCNF is that every arrow in every FD is an arrow that comes out of a candidate key. In R, the arrow in "C->D" doesn't come out of a candidate key.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.