NIELIT 2017 OCT Scientific Assistant A (IT) - Section B: 16

Question

For a database relation $R(a,b,c,d)$ where the domains of $a,b,c$ and $d$ include only atomic values, only the following functional dependencies and those that can be inferred from them hold.

• $a \rightarrow c$
• $b \rightarrow d$

The relation is in

• A. First normal form but not in second normal form
• B. Second normal form but not in third normal form
• C. Third normal form
• D. None of the above

Answer 1

a->c
b->d
candidate key is only one: {ab}
so key attribute is : a and b
and non-key attribute is: c and d
{*for 2nf f.d. should free from partial dependancy*}
{*partial dependancy= (part of key->non-key attribute)*}

in given question partial depency is present so it is not in 2nf.

hence, option A is correct.

Answer 2

there is partial dependencies as ab is candidate key ,

so this relation can’t be in 2^nd niormal form ,

hence option A is correct .