GATE CS Applied Course

1nf 2nf


is it necessary ,if it is in 1 nf or 2 nf or 3 nf then it must be lossless and dependency preserving? in bcnf can we have a case where it is not lossless but dependency preserving



Jnana Bhaskar Akhil Idury Posted on Dec 03, 2019 11:03 PM

Actually, 1NF , 2 NF and 3 NF preserves dependency and Lossless join. But, sometimes , BCNF fails to preserve Dependency.


Vikas Posted on Dec 23, 2019 01:46 PM

Yes, it is necessary to have a lossless decomposition in 1nf,2nf,3nf and bcnf but we cannot guarantee dependency preserving FDs in BCNF.


Tushar Posted on Dec 23, 2019 01:55 PM

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