Re: trees in MySQL

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The difficulty you are being confronting could be alleviated by using an XML data model (meaning non relational). Of course, I don't know about your requirements, but it could be a direction worth investigating.

I use the php_xslt.dll (sablotron) extension, which I find works quite pleasantly.

Ignatius
____________________________________________
  ----- Original Message -----
  From: "José Moreira" <jmoreira@e-terno.net>
  To: "Php-Db (Correio electrónico)" <php-db@lists.php.net>
  Sent: Thursday, December 19, 2002 11:45 AM
  Subject:  trees in MySQL


  > hello im implementing a portal and im choosing between the 'Nested Set'
  and
  > 'Adjacency Lists tree' models.
  > <http://users.starpower.net/rjhalljr/Serve/MySQL/traer.html>
  >
  >
  > im perfectly aware of the 'Adjacency Lists tree' model how-to and I am
  > studying the 'Nested Set', example follows :
  >
  > CREATE TABLE LanguageTree (
  >
  >   Language VARCHAR(255) PRIMARY KEY
  > , Parent VARCHAR(255)
  > , Lft LONG
  > , Rgt LONG
  > , INDEX idxLft (Lft)
  > , INDEX idxRgt (Rgt)
  > ) Comment = "Related languages";
  >
  >
  >     A[1 12]
  >   /          \
  > /   \
  >     B[2 3]       C[4 11]
  >    /          \
  >   /            \
  >   D[5 8]     F[9 10]
  >      |
  >   E[6 7]
  >
  >
  > my doubt is that if i want to insert a new node, for example 'G' under 'A'
  >
  >     A[1 12]
  >   /     |     \
  > /          \
  >     B[2 3]    G[]   C[4 11]
  >    /             \
  >   /               \
  >   D[5 8]         F[9 10]
  >      |
  >   E[6 7]
  >
  >
  > i have? to update almost every left,righ fields after that node, resulting
  > in a website performance downgrade ....
  >
  >
  > help? even if thjats the only way, how can i do it? perhaps im getting it
  > wrong ...
  >
  >
  > best regards
  >
  >
  > José Moreira
  > TEGOPI S.A.
  > http://www.tegopi.pt
  >
  >
  >
  >
  >
  >
  >
  >
  >
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