tree traversal

[spstieng]

I've done a bit of research on hierarcical databases and have found that tree traversal is a good way of building a hierarchical db.

But I'm struggeling a bit on how to put theory down to hardcore code :eek:

So I was wondering if anyone have done this with PHP.
I'm on Apache 2 with PHP and MySQL.

I think the biggest problem is adding or removing elements inside the tree. If you have a HUGE databse, it seems very inefficient to update RIGHT and LEFT columns for the entire database whenever adding / removing an element.

I guess there is a up and down side to every solution :rolleyes:

The best resouce I have found on hierarchical DB is
here:

Have anyone done something similar and can give me a few pointers / PHP examples?

Thanks.

[tomhath]

I don't understand what you're trying to do. If you want to look up records quickly, put an index on the table (it very likely builds a tree structure for you).

Here's an implementation:

http://coldstore.sourceforge.net/coldstore/kdoc/BTree_hh.html

[ultraslacker]

Celko has dedicate a book on tree structures in sql - check out this page for some idea of how to update the nodes, as well as basic tree traversal algorithms.

If the tree structure will get heavily modified, then you may want to separate structure from node.