Describe the two approaches to converting an Unnormalized Normal Form (UNF) table to First Normal Form (1NF) relation(s).

Question

What will be an ideal response?

Answer 1

There are two common approaches to removing repeating groups from unnormalized tables:
(a) By entering appropriate data in the empty columns of rows containing the repeating data.
In other words, we fill in the blanks by duplicating the nonrepeating data, where required. This approach is commonly referred to as ‘flattening’ the table.
(b) By placing the repeating data, along with a copy of the original key attribute(s), in a
separate relation. Sometimes the unnormalized table may contain more than one repeating
group, or repeating groups within repeating groups. In such cases, this approach is applied
repeatedly until no repeating groups remain. A set of relations is in 1NF if they contain no
repeating groups.
For both approaches, the resulting tables are now referred to as 1NF relations containing
atomic (or single) values at the intersection of each row and column. Although both
approaches are correct, while approach (a) introduces more redundancy into the original UNF
table as part of the ‘flattening’ process, approach (b) creates two or more relations with less
redundancy than in the original UNF table. In other words, approach (b) moves the original
UNF table further along the normalization process than approach (a). However, no matter
which initial approach is taken the original UNF table will be normalized into the same set of
3NF relations.