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I have normalized some tables up to 2nd normal form.

Below are the normalized tables.

enter image description here

I am really confused with the 3 normalization phase as it is some what similar to 2nd normalization phase. My question is, is the nurse table already in the 3rd normalization phase or not ?

Also can some one explain me , what is the difference between the 2nd normalization form and 3 normalization form. I know that 2nd normalization form has partial dependencies and 3rd normalization form has transitive dependencies but still am a bit confused.

Thank you for your time.

Troller
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1 Answers1

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The difference between 2NF and 3NF is this. Suppose that some relation satisfies a non-trivial functional dependency of the form A->B, where B is a nonprime attribute.

2NF is violated if A is not a superkey but is a proper subset of a candidate key

3NF is violated if A is not a superkey

"Superkey" just means any set of attributes that includes a candidate key of your table.

Therefore if a relation satisfies 3NF then it already satisfies 2NF. In that sense, 2NF itself is not especially important. Actually 3NF is not especially important either. Boyce-Codd Normal Form is more important but I guess this is homework and you are expected to study 2NF and 3NF first.

No one can say for sure whether your design satisfies 3NF or not because you haven't said what dependencies it is supposed to satisfy. Judging by the names of your attributes it seems unlikely that your design is correct. It appears that a nurse can only be assigned one patient at a time, which I guess would not be right.

nvogel
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  • Thank you for your great answer. According to the scenario which was give to me , a nurse can only be assigned to one patient. Thanks again for clearing the doubts between the 2nd and 3rd nf – Troller Jan 18 '14 at 06:28