Posted by nospam on 09/16/05 20:55

Hi all,

I'd like to implement a tree of "tags" for a blog I'm writing for fun in PHP.
Here's what a single tag looks like:


CREATE TABLE tags
(
name varchar(30) not null default '',
id_self integer(12) not null primary key,
id_parent integer(10) not null default 0,
);
INSERT INTO tags VALUES ('root of the tree', 0, 0);


Each tag has a name, a unique id to identify itself with and a parent's id,
and all this will be stored in a database, but stored in no particular order.

I'm a little stumped as to how to reconstruct the tree. Part of the problem
is that suppose my first read to the database yeilds:

name = "physics"
id_self = 21
id_parent = 2


but further down in the database, this record exists:

name = "science"
id_self = 2
id_parent = 0

in other words, it's possible that children may be read before parents.


I've noticed that some people have implemented a tree class. Since this is
supposed to be a *fun* project for me, I'd rather write it myself. But I
find myself staring at the keyboard, not knowing how to start.

How can I reconstruct this tree?

Thanks!
Pete

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