A non key shouldnt be fully functionally dependent on a subset of Ck

It must be "PROPER subset". But what's the significance of "fully" here?

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Consider the following dependencies and the BOOK table in a relational database design. Determine the normal form of the given relation.

ISBN $\rightarrow$ Title

ISBN $\rightarrow$ Publisher

Publisher $\rightarrow$ Address

- First Normal Form
- Second Normal Form
- Third Normal Form
- BCNF

+8 votes

Best answer

The relation is in second normal form .

We first need to find Candidate key by taking closure of attributes = ISBN

Now with ER modelling we get relation in 1 NF .

for 2nf , we shouldnt have any partial dependency ( A non key shouldnt be fully functionally dependent on a subset of Ck )

Since our Ck is 1 attribute only we wont have that partial dependency

But now for 3nf , if you see we have Address which is transitively dependent on ISBN . Hence Transitive dependency exists .

So relation is in 2nf and not in 3nf

We first need to find Candidate key by taking closure of attributes = ISBN

Now with ER modelling we get relation in 1 NF .

for 2nf , we shouldnt have any partial dependency ( A non key shouldnt be fully functionally dependent on a subset of Ck )

Since our Ck is 1 attribute only we wont have that partial dependency

But now for 3nf , if you see we have Address which is transitively dependent on ISBN . Hence Transitive dependency exists .

So relation is in 2nf and not in 3nf

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