Don't worry I found the solution on the great information super landfill (the real reason for global warming) the interweb.

One uses left/right values of a defined range for each node...

I see how it deals with finite known sets of data, but how does it cope with new records, positional changes and deletions?

Or is this too big a topic to...

Ok I found it

http://www.dbmsmag.com/9603d06.html

Whoa thats like 12 years old almost. 😀

--Shaun

Jeff do you have a link to Celko's "nested model"?

--Shaun

My view on is that McFarland has answered the initial question but it is only treating a symptom and is not the cure, it solves the poster's issue.:D

The question is...

I said I agree with you. 😀

Just doing my question everything/trust nothing routine. 😀

What is the purpose of the original request? How will the result be used?

p.s. original poster =...

antonio - though I do not disagree with you, I would still like to know the context of the question.

but i still think a parent child relationship would be better...

Brent McCracken

I do not see how your data structure is easily usable without jumping through hoops;

The only way to implement this with ease is with two columns - parent...

If you do as Gail suggests make StudentID/CourseID a compound key nulls would not be allowed anyway.:)

--Shaun

Why have only one column?

Why not one for parent and one for child?

Is your table structure immutable?

--Shaun

Erm..should you really allow nulls in your relationship tables?

I don't think so because for the relationship record to exist both of the entities in the relationship must exist.

e.g. StudentCourse(Instructor) both...

Hmm...do you have the mathematical proof that 0 raised to 0 is undefined?

What make is your calculator?

Whoops! We've hijacked a thread!:D

However my reasons for 0^0 = 1

http://mathforum.org/dr.math/faq/faq.0.to.0.power.html

Hey Terri...

0 to the power 0 is undefined - maybe in pure maths

But my good ol calculator says it is 1. 😀

--Shaun

In my experience its not the cutting of code that is the problem.

One should always build quality software.

Its the people, especially those in charge, and they are usually the bean...

Damn! I should proof read what I type

14 base 16 is 20 in base 10

Doh!

But hey 2 out of 3 = 66% must be worth a 2/2 Degree 😀

--Shaun