Consider the following ER diagram:
How many number of relations are required for the above ER diagram?
- 2
- 3
- 5
- 1
Solution:
My doubt is:
Since $E_2$ isn’t involved in total participation with $E_1$ so on merging we might get 2NF violation.
Eg:
Let $E_1$ be:
<p1,q1>
<p2,q1>
<p3,q2>
$p \rightarrow q$
Let $E_2$ be:
<r1,s1>
<r2,s2>
<r3,s2>
<r4,s3>
$r \rightarrow s$
And p1 maps to r1, p2 maps to r2 and p3 maps to r3.
Merging with $E_2$ will give:
<r1,s1,p1,q1>
<r2,s2,p2,q1>
<r3,s2,p3,q2>
<r4,s3,NULL,NULL>
$pr \rightarrow sq$
$r \rightarrow s$
$p \rightarrow q$
2-NF violation.
So by default which case is to be considered when normalization form is not mentioned?? 1-NF?
