> I want to design the foreign key scheme such that there are relationsbetween
> fruit and apple, and fruit and orange, that imply that apple isa fruit,
> and orange is a fruit.
Sometime in the future, you will be able to achieve this beautifully and easily using postgresql's
feature known as table-inheritance. Right now it can already support hierchey between different
types of fruit, however it does not allow for foreign key relationships.
However, I figured out a work-around using seperate a table for each entity of the heirchey. And
then I rolled up these entities using views made update-able with the Postgresql rule system.
Here is a link were I present how it is done.
http://archives.postgresql.org/pgsql-general/2006-12/msg00913.php
Let me know if you have any questions.
Regards,
Richard Broersma Jr.
