Hi, Suppose you have a relation with attributes ABCDEFG with functionaldependenc

Question

Hi,

Suppose you have a relation with attributes ABCDEFG with functionaldependencies A->ABCDEFG, CD->A, BE->CF. Answer thefollowing (4 pts each).

a) List one additional (nontrivial) functional dependency that youcan figure out

This may not be right because it seems way to easy, to simply justadd D to both sides, the professor did show this though on theslides so it may work, just making sure.

BE-> CF -> BDE-> CDF
                                  
List 3 keys for this relation.
I think A would be a Key
CD would be a Key
and BDE would also be a key right?

I don't think there are any others, just making sure

Explanation / Answer

Question 4: Suppose you have a relation with attributes ABCDEFGwith functional dependencies A->ABCDEFG, CD->A, BE->CF.Answer the following (4 pts each). a) List one additional (nontrivial) functional dependencythat you can figure out we know that BE-> CF ==> BDE->CDF                                      ==> BDE--> AF [since CD->A]                                      ==> BDE-->A , BDE --> F Hence BDE --> A is a nontrivialfunctional depndency which can be derived using the abovethree functional dependencies. b) List 3 keys for this relation. 1)A is key since A->ABCDEFG [A uniquelydetermines all A,B,C,D,E,F,G] 2)CD is also a key since CD-->A and A is a key,so CD can uniquely determine all A,B,C,D,E,F,G 3)BDE is also a key since BDE--|>A(proved inthe first part). As A is a key and BDE-->A. now BDE can alsouniquely determine all od A,B,C,D,E,F,G

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