Do these definitions sound correct andalso the benefits/drawbacks of BCNF/3NF? P

Question

Do these definitions sound correct andalso the benefits/drawbacks of BCNF/3NF?

Pros: No redundancy
Cons: could result in more expensive queries

The third normal form (3NF) is a normal form used in databasenormalization. 3NF definition states that a table is in 3NF if andonly if both of the following conditions hold:

    * The relation R (table) is in second normalform (2NF)
    * Every non-prime attribute of R isnon-transitively dependent (i.e. directly dependent) on every keyof R.

Benefits: losslessdecomposition
Drawbacks: May still have redundancy (BCNF isbetter).

Thanks! just double checking!

Explanation / Answer

a) BCNF: Every functional dependency A-->B in aset of functional dependencies of relation R should satisfyeither 1)B is a subset of A or 2) A is a superkey of relation R Benefits: No redundancy, Decompostion of the relation willbe lossless Drawbacks: Not Dependency preserving b) 3NF: Every functional dependency A-->Bin a set of functional dependencies of relation R should satisfyeither 1)B is a subset of A or 2) A is a superkey of relation R or 3) B is a subset of some key of R Benefits: 3NF is dependency preserving,Decompostion of the relation will be lossless Drawbacks: Some problem of redundancy

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