Unnormalized Form Oracle Tips by Burleson Consulting

The Data Warehouse Development Life Cycle

Oracle Data Warehouse Design

Unnormalized Form

Essentially, an unnormalized relation is a relation that contains repeating values. An unnormalized relation can also contain relations nested within other relations, as well as all kinds of transitive dependencies. Sometimes unnormalized relations are signified by 0NF, but an unnormalized relation is not to be confused with a denormalized relation. The unnormalized relation is any relation in its raw state, and they commonly contain repeating values, and other characteristics that are not found in denormalized relations. The process of denormalization is a very deliberate attempt to introduce controlled redundant items into an already normalized form.

Today, only a handful of database management systems support repeating values, including UniSQL and some object databases. The relational database model requires that each column within a table contains atomic values, and there is no facility for indexing multiple occurrences of a data item within a table. The idea of repeating groups was first made popular with the use of the Cobol language with IS-AM files. For example, a Cobol working storage definition could allow for repeating occurrences of items, as follows:

03 order_form.
     05 customer_name pic x(80).
     05 customer_address pic x(80);
     05 ordered_items occurs from 1 to 10 times depending on number-ordered.
         07 item_number pic s9(8) comp3.
         07 item_description pic x(80).
         07 quantity_ordered pic 9(4).

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