Re: Inheritance or no inheritance, there is a question

Vernon,

> What is the best solution for this DB scheme problem?

Have you considered not using inheritance? As a relational-SQL geek myself,
I'm not keen on inheritance -- I feel it mucks up the relational model. Not
everyone agrees with me, of course.

Personally, I'd suggest the following structure:

Profile A
id Primary Key
detail1
detail2

Profile B
id Primary Key references Profile A ( ID )
detail 3
detail 4
detail 5

Profile Languages
id not null references profile A ( ID )
language id
primary key id, language id

etc.

In this way, Profile B is a child table with a 1:0-1 relationship with Profile
A. Multi-value dependancies, like Languages, can be related to either the
people who belong to the B group (and, by implication, the B group) or the
people who belong to the A group only.

Want the B group? SELECT A JOIN B
Want the A group only? SELECT A EXCEPT B

This is the "relational" way to approach the problem.

--
Josh Berkus
Aglio Database Solutions
San Francisco