Wednesday, July 9, 2003, 5:13:02 PM, you wrote:
MR> Jon Hall wrote:
>>I looked at this method and all the others, and decided to go
>>with the non-traditional method outlined here.
>>http://www.planet-source-code.com/vb/scripts/ShowCode.asp?
>>txtCodeId=7321&lngWId=4
MR> Thats actually a fairly old idea. Always seemed to me that inserting records or
reordering would be a great big PITA.
MR> Nice bit of attitude copped by the author at the end of his little dissertation.
I speak not for this guy...except to say he sounds pretty typical of
the average VB dork's I run into. If I could find this method
documented elsewhere...believe me I would have posted it instead. :)
Inserting is fairly easy as long as you have the parent, and the
number of records in the subtree you are looking to insert into.
One line of code actually + the insert.
<cfset newserial = parentSerial + numberFormat(val(right(cat.serial[cat.recordCount],
3)) + 1, "000")>
I haven't implemented a reindexer using this method...but it would
need to be an offline one if the tree was too big. I haven't run into
the need yet for one though. To me, the unbeatable speed of this
method in reading a sorted tree is worth a bit of kludginess in the
implementation though.
This is my post from the cfczone list about it...
Tuesday, June 17, 2003, 8:30:04 PM, you wrote:
AC> I'm still interested to know how the "build a key out of a hash of the
AC> node and its depth in the tree" (or whatever it is... I delete these
AC> posts as I read them, so forget the details) copes with moving a node to
AC> elsewhere in the tree?
Pretty easily...
Say I have a model like this (which I do use), similar to Matt's abc
type tree except it allows 999 nodes instead of 26 at the expense of
larger keys.
Name Serial
Cars 001
Ford 001001
Jaguar 001001001
Volvo 001001002
Lincoln 001001003
GM 001002
Buick 001002001
Cadillac 001002003
Escalade 001002003001
DeVille 001002003002
Say GM sells Cadillac to Ford, I need to move the 001002003* tree
below 001001. So it's one simple UPDATE statement using the LIKE
keyword to update everything that begins with 001002003 to 001001 +
(next unused tree node). This model does end up updating a lot of rows
with very large trees, so I have my doubts as to how far it would
scale, but it's extremely simple and fast enough for every tree I've
done.
The actual SQL would end up looking something like this...
UPDATE Categories
SET Serial = '001001004' + SubString(Serial, (Len('001001004') + 1), Len(Serial) )
WHERE Category_ID LIKE '001002003%'
--
jon
mailto:[EMAIL PROTECTED]
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