modified preordered tree traversal (was RE: [thelist] CF: Valuestransposition. Too ugly, needs a face lift.)

[Luther, Ron]

Joel asked:

>>Anyway, is there more out there about modified preordered tree 
>>traversal? Is there a 'definitive document' or is that tutorial it?


Hi Joel,


Mark brought up Oracle's "support" for traversing hierarchical trees.

(Yeah - I put "support" in quotes on purpose ... Cuz I've tried 
to wrestle with that bear in the past.  [Attempting to pull 
multi-level manufacturing 'bill of material' information out of 
one of these Oracle structures.]  ;-(  I had an easier time 
building my own clunky, Rube Goldberg style work-around to pull 
the information out of those kinds of data structures. This stuff 
can get real ugly real fast.)

Here's the relevant section of an Oracle tutorial by 'the man', 
(Phil Greenspun):
http://philip.greenspun.com/sql/trees.html

Phil writes very well, and there might not be _anybody_ who 
understands this stuff better.  Phil is top shelf.  This would 
be my closest guess at a 'definitive tutorial'.


Or maybe try an article from another db wizard. (I haven't read 
too much by him - but Rudy always brings this guy's name up, 
(Joe Celko), so you *know* he must be pretty damn sharp!): 
http://www.dbazine.com/ofinterest/oi-articles/celko24


Good Luck!


HTH,

RonL.