Explain nested relations?

Nested relations

The assumption of INF is a natural one in the bank examples we have considered.

However, not all applications are best modelled by INF relations.

The nested relational model is an extension of the relational model in which domains might be either atomic or relation valued.

We illustrate nested relations by an example from a library. Assume we store for every book the following in formations

 Book title

Set of authors

Publishers

Set of keywords

We can see that if we describe a relation for the preceding information, several domains will be monatomic

Authors

Keywords

Publishers

Complex types

Collection and large object types

Create table books(

...

Keyword-set setoff(varchar(20))

           ...

            )

            Structure types

            Creation of values of complex types