Articles tagged

07 May 2009
07 May 2009

Facts and Fallacies about First Normal Form

When discussing the normalisation process, it is always the First Normal Form that causes the most grief and confusion. Anith Sen takes up the challenge to explain, in simple terms, exactly what the First Normal Form really is, and why it is so important for Database Design. Along the way, he dispels some of the myths that have grown up around 1NF.… Read more
18 November 2008
18 November 2008

Unique Experiences!

You'd have thought that a unique constraint was an easy concept - Not a bit of it; it can cause a lot of subtle problems in database designs. Joe Celko goes over the ground of unique keys, primary Keys, foreign keys and constraints.… Read more
01 April 2008
01 April 2008

The Concept of Cardinal Reciprocity- A Primer

Too many authors in the field of relational theory have neglected the concept of Cardinal Reciprocity. This can cause a number of subtle problems with database design in terms of its derivability, redundancy, and consistency. . Increasingly, this little-understood aspect of relational theory, that emphasises the cardinality of the attributes of tuples in a relation and the reciprocity with isomorphic foreign key restraints, is becoming a hot forum topic.… Read more
22 February 2007
22 February 2007

Database Design: A Point in Time Architecture

In most relational database implementations. Update and Delete commands destroy the data that was there prior to their issue. However, some systems require that no information is ever physically deleted from or updated in the database. In this article, Arthur Fuller presents a solution to this requirement in the form of a Point-in-Time architecture: a database design which allows a user to recreate an image of the database as it existed at any previous point in time, without destroying the current image.… Read more
17 February 2006
17 February 2006

Intelligent Database Design Using Hash Keys

Your application may require an index based on a lengthy string, or even worse, a concatenation of two strings, or of a string and one or two integers. In a small table, you might not notice the impact. But suppose the table of interest contains 50 million rows? Then you will notice the impact both in terms of storage requirements and search performance.… Read more