Relational Databases Oracle Tips by Burleson Consulting

High Performance Data Warehousing

Introduction Of The Relational Model

Dr. Ted Codd, a researcher from IBM, developed a model for a relational database in which the data resided in pointerless tables. Relational database tables can be navigated in a declarative fashion, without the need for any database navigation. Dr. Codd called these tables, relations. Relations within his model are very simple to conceptualize, and they can be viewed as two-dimensional arrays of columns and rows. Codd's relational model contains a set of relational criteria that must be met before a database can be truly relational. It is interesting that Dr. Codd's model of relational characteristics is so stringent that no company has yet offered a commercial database which meets all of his criteria.

Relational databases provide the following improvements over earlier database architectures:

* Data independence--The data resides in freestanding tables, which are not hard-linked with other tables. Columns can be added to relational tables without any changes to application programs, and the addition of new data or data relationships to the data model seldom requires restructuring of the tables.

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This is an excerpt from "High Performance Data Warehousing", copyright 1997.

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