5. Assume you have FDs, G-A--B, A--C, ? ?, ?-»D, C D, D A), what is the primary

Question

5. Assume you have FDs, G-A--B, A--C, ? ?, ?-»D, C D, D A), what is the primary key? AB (meaning A&B; together form the primary key.] b) a) BC (meaning B&C; together form the primary key) CD (meaning C&D; together form the primary key) c) d) any single attribute A, B, C, or D can be the primary key 6. Is the set of FDs, G, from the previous question minimal? a) yes, because we don't want to lose any functional dependencies b) yes, because the right-hand side of each dependency has just one attribute c) no, because I of the functional dependencies is redundant d) no, because 2 of the functional dependencies are redundant

Explanation / Answer

Answer is as follows:

1) The Correct Option is d. because any of single attribute defines the primary key.

As follows :

{A}+ = { A,B,C,D}

{B}+ = { B,C,D,A}

{C}+ = { C,D,A,B}

{D}+ = {D,A,B,A}

2) The Correct Option is A i.e. because we don't want to lose any functional dependency.

No redundant functional depenencies are there. These are those dependencies that are derived from another dependencies. But in this case they all are defined by itself.

If there is any query please ask in comments...

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