Database - The Relational Model and Normalization - Discussion

Discussion :: The Relational Model and Normalization - General Questions (Q.No.1)

1. 

Every time attribute A appears, it is matched with the same value of attribute B, but not the same value of attribute C. Therefore, it is true that:

[A]. A → B.
[B]. A → C.
[C]. A → (B,C).
[D]. (B,C) → A.

Answer: Option A

Explanation:

No answer description available for this question.

Abhishek Tamrakar said: (Mar 2, 2011)  
Beacause only value of A will match with B.

So A->B is true.

Aani said: (Apr 15, 2011)  
Because of logical signs properties.

Shrav said: (Jul 5, 2011)  
A can uniquely identifies B each time so A->B

Honey said: (Oct 3, 2011)  
What is it's meaning---- A->B..?

Runa said: (Feb 3, 2012)  
A->B means the occurence of A attribute with B eyery time.

Chandra said: (Mar 1, 2012)  
A->B every attribute in A should match with B.

Ouen said: (Mar 27, 2012)  
Value of B depends on value of A; i.e. A is uniquely determined B

Khalid Seid said: (Feb 7, 2013)  
Value of B depends on value of A. i.e A is the determinant but B is the dependent.

Nivikpr said: (Jul 31, 2013)  
As per the rule A->B means if A is true then B is true.

Vishnu said: (Oct 20, 2013)  
The functional dependency A->B states that the set of values present in A are also in the B so that's why it matches the values in the case of A and B but not with C.

Richa Chaurasia said: (Apr 2, 2014)  
Because of every attribute of A will also match with B but not C.

And then value of A $ B will depend to each other.

A->B.

Rahul said: (Apr 26, 2014)  
A -> B means that, each value of A determines exactly one value of B. And B is functionally dependent on A.

Shivakavya said: (Nov 12, 2014)  
Because A can uniquely identifies B each time.

So A->B. Option A.

Kash said: (Dec 12, 2014)  
It is a general thing to be noticed that if A will be related to both B & C, then how can the value not be same to C. So option A is correct. !

Rahul Kumar said: (Mar 31, 2015)  
According to question A->B.

That means A would have all the contents such as that of B.

So instead of using tends to operation. Here have to use the UNION operation (A U B).

And guys please look forward for this.

Arshad said: (Jul 8, 2015)  
A is functionally dependent on B.

Padmasri said: (Jul 9, 2015)  
Because A can uniquely identifies B each time.

As per the rule A->B means if A is true then B is true.

Harsh Dusane said: (Sep 3, 2015)  
Because here A functionally determines B but not C so A->B.

Emil said: (Dec 12, 2015)  
Is A-->B is same as B-->A. A matches with B, so is it true that B matches with A?

Sefu Julius said: (Jul 5, 2016)  
The correct answer is A->B.

Shahin said: (Feb 28, 2017)  
@Emil.

If A -> B holds then it's not necessary the B -> A also hold true.

A B
----------------------------
b 5
b 5
c 5

For every occurrence of b in A there is value 5 in B hence A -> B.
But for every Value of B which is 5 is not same value in A (b,c two values in A).
Hence If A -> B holds then it's not necessary that B -> A also holds true.

Elias Joseph said: (Jul 3, 2017)  
Answer is A because in a change of a implies that also b change.

Harsha said: (Jun 20, 2019)  
Because A is functional to B is less than or greater than to it.

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