NIELIT 2016 DEC Scientist B (CS) - Section B: 49

Question

Considering relational database, functional dependency between two attributes $A$ and $B$ is denoted by

• A. $A\to B$
• B. $B\gets A$
• C. $AB\to R$
• D. $R\gets AB$

Answer 1

Option A. A -> B

Functional Dependency is  one attribute determines another attribute in a DBMS system. Here A determines B i.e., with A attribute we can derive attribute B.

Comments

yea,but is B <-- A not same as A-->B ?

if so why?

Both mean A is functionally depending on B.

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B <-- A is  not same as A-->B .

Because of this <-- symbol. If it is this -->, it will be one of the  correct option.

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so whats difference between --> and  <--

Answer 2

ANS : A

Relational database, functional dependency between two attributes AA and BB is denoted by

 

A→B

WHERE A IS CALLED AS DETERMINANT .A DETERMINE B