Why bcnf is stronger than 2nf

Normalization is done through normal forms. The standard normal forms generally used are- In this article, we will discuss some important points about normal forms. A relation in 2NF will surely be in 1NF.

This is because if it is found to be in BCNF, then it will surely be in all other normal forms. If the relation is not in BCNF, then start moving towards the outer circles and check for other normal forms in the order they appear.

Point Singleton keys are those that consist of only a single attribute. If all the candidate keys of a relation are singleton candidate keys, then it will always be in 2NF at least.

This is because there will be no chances of existing any partial dependency. The candidate keys will either fully appear or fully disappear from the dependencies.

Thus, an incomplete candidate key will never determine a non-prime attribute. Since there are no non-prime attributes, there will be no Functional Dependency which determines a non-prime attribute. Point If all the attributes of a relation are prime attributes, then it will always be in 3NF at least. This is because there will be no chances of existing any transitive dependency for non-prime attributes. Point BCNF is free from redundancies arising out of functional dependencies zero redundancy.

In other words, a relation with no non-trivial functional dependencies is always in BCNF. Point BCNF decomposition is always lossless but not always dependency preserving.

But in the real world database systems, it is generally not required to go beyond BCNF. Apa itu Scribd? Diunggah oleh Alyssa C. Apakah menurut Anda dokumen ini bermanfaat? Apakah konten ini tidak pantas? Laporkan Dokumen Ini. Tandai sebagai konten tidak pantas. Unduh sekarang. Judul terkait. Karusel Sebelumnya Karusel Berikutnya. Lompat ke Halaman. Cari di dalam dokumen. Saima Malik. Melissa A. Fenil Desai. Hafiz Fizul.

Denny England. Anthony Beltran. Jeff T. Fedrich De Marcus. The table in this example is in 1NF and in 2NF. An atomic value is a value that cannot be divided. A repeating group means that a table contains two or more columns that are closely related. First normal form 1NF As per the rule of first normal form, an attribute column of a table cannot hold multiple values. Second normal form 2NF is a normal form used in database normalization.

A relation is in the second normal form if it fulfills the following two requirements: It is in first normal form. It does not have any non-prime attribute that is functionally dependent on any proper subset of any candidate key of the relation.

Second normal form: A relation is in second normal form if it is in 1NF and every non key attribute is fully functionally dependent on the primary key. All attributes a single valued 1NF.