Assuming that SubjectCode and SubjectName are both candidate keys for the Subject entity, there is no reason to have both these fields here. In Carlo Zaniolo produced a differently expressed definition for 3NF. For a table to comply with 2NF, it should be complied with 1NF and any attribute that is not a part of any candidate key i.
Therefore in general, obtaining a table that complies with the 3NF form will require decomposing a table that is in the 2NF. Similarly, obtaining a table that complies with the 2NF will require decomposing a table that is in the 1NF.
If we ask the question of an attribute and the answer is not all or part of the candidate key, then the tuple is not in 3nf. Fine, this is one of the candidate keys. Codd, who is also the inventor of the relational model and the concept of normalization.
These smaller tables will be related to each other through well defined relationships. We need to know the student, the subject and the exam being taken.
However, at one point I said "this tuple is not in 2nf," which more properly should have been, "this entity is not in 2nf. Remove it from this tuple and it is now in 2nf.
However, if a table that complies with 1NF contains candidate keys that are only made up of a single attribute i.
One important property is that a table that comply with 1NF could not contain any attributes that are relational valued i. So we may safely get rid of the SubjectName field altogether without sacrificing any integrity of the model.
However, in my original answer, in my desire to show another level of normalization, I ignored that SubjectName had been used in a candidate key and considered it just another non-prime attribute. In this case, there is only one: This process will mainly divide large tables in to smaller tables with fewer redundancies.
One unique reference to a row in the Subjects table is quite enough.1NF, 2NF, and 3NF are _____. normalization stages. From a structural point of view, 2NF is better than _____.
1NF. Normalization works through a series of stages called normal forms. For most purposes in business database design, _____ stages are as high as you need to go in the normalization process. Explaining 2NF vs 3NF with an example. up vote 12 down vote favorite.
1. I have a problem with second normal form (2NF) and I have been unable to solve it by using Google. It is making me crazy because I am a teacher and I don't want to teach wrong stuff to my students.
2nf Authentication Better Than 1nf Essay Is two factor authentication better than one-factor authentication?
Critically appraise this using concept of security goals and implementation. OP- 10% orAssignment- 15% The impact of the internet over the last few years has meant fundamental changes in the way we access the information.
Normalisation Forms • 1NF • 2NF (better than 1NF) • 3NF (better than 2NF; most of the time as high as needed for businesses databases) • Boyce-Codd NF • 4NF Pitfalls of Normalisation A higher normalisation level is not necessarily the best.
the first the stages are described as 1st normal form (1NF), 2nd normal form (2NF), and 3rd normal form (3NF). From a structural point of view 2nd normal form (2NF) is better than 1st normal form (1NF), and 3rd normal form (3NF) is better than 2nd normal form (2NF). What is the difference between NF, 2NF, and 3NF?
Update Cancel. ad by mi-centre.com 1NF, 2NF, 3NF, and 4NF are part of Oracle dbms? What is the difference between using view and with (select)?
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