Question - What does the term unnormalized relation refer to? How did the normal forms develop historically from first normal form up to Boyc-Codd normal form?
Answer -
Unnormalized relation will contain update,insert,deletion anamolies. 1nf will remove repeating colums. 2nf will remove subsets of data. In 2nf every non-key attribute should depend on entire primary key
In 3nf, all columns should depend directly upon primary key and transitive dependency should be removed(a->b b->c c->a).
In 4nf, multivalued dependancy should be removed.
In BCNF, every determinant should be a candidate key.