we are already using the same logic you explained for sql server 2005.
we don't have sql server 2000, so we don't have to call a stored procedure recursively.
we have several sorts of multilevel network marketing implementation.
some companies which use similar business logic are amwa_ and for_v_rlivin_
this can be viewed as layers or tiers.
the whole hierarchy can be called trees, stars or simply networks.
in one of our cases, we are limited to a table with columns parent, tier2, tier3, ..., tier10.
i guess, i would need to rewrite ddl for this table with hierarchyid, but later this change will imply changing a lot sql logic already written. this can be done because this client has sql server 2008.
it looks simple, but any tiers, including parent column, can have multiple rows, and of course some tiers are plain null, except by parent column.
we have successfully drawn trees from these tables, for which the hardest case is this table with columns parent, tier2, tier3, ..., tier10.
one of these trees is in a flex front-end, and the other is an asp.net treeview as gui.
your article has given me plenty of insight about tree structure business logic, and i stopped by to say thank you.
my guess is that hierachyid is in our short-term future for database programming.
keep up your good work!!