CODEWITHSUNDEEP
sqlnormalizationdatabase-normalization
Steph
Steph

Reputation: 19

Why is this in 2nd Normal Form

Given a table consisting of the attributes R = [U, V, W, X, Y, Z] and the functional dependencies: F = {UV->WXYZ, VW->Y, Y->Z}

I have determined that the possible candidate key for the table R is UV.

When it comes to determinig the highest normal form I think that the table is in 1st normal form. 1NF because part of a key determines a value in the table (VW -> Y). According to the answers that the teacher provided the table is in 2nf can anyone clarify why this is?

Upvotes: 0

Views: 128

Answers (2)

Pablo Prado
Pablo Prado

Reputation: 193

You said it yourself, part of a key has to determine another value. If your key is UV, then U or V have to determine something else to break 2NF. The fact that VW has V in it is irrelevant in the definition, since it has to be that U by itself or V by itself have to determine something.

Good luck tomorrow!

Upvotes: 1

Russ
Russ

Reputation: 4173

A table in Second Normal Form is also in First Normal Form--that is one of the requirements for Second Normal Form (http://en.wikipedia.org/wiki/Second_normal_form). If every column (W, X, Y, and Z) are all dependent on the entire composite key (U and V), then the table is in second normal form. If one column only needed part of the key and would duplicate for the same value of that one part, regardless of the value of the second part, then the table is NOT in Second Normal Form.

Without any knowledge of the data, this is the best answer that can be provided.

Upvotes: 1

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