LIS 558 - Rules for relation generation from ER type diagrams

(Adapted from Jackson, G. 1988. Relational database design with micro-computer applications.)

A relation is required for each relationship with the following exceptions:

The primary key for a relationship relation may be either entity key if the relationship is 1:1. If the relationship is 1:n, the primary key should be the entity key on the n side; and, if the relationship is m:n, the primary key should be a composite of the two entity keys.

A relation is required for each entity class in a relationship with the following exception:

The primary key for an entity class relation is always the entity key.
Home

Last updated July 7, 2000.
This page maintained by Prof. Tim Craven
E-mail (text/plain only): t.craven@uwo.ca
Faculty of Information and Media Studies
University of Western Ontario,
London, Ontario
Canada, N6A 5B7