I almost always use "adjacency lists" along with another table for the
actual categorization of the info (in your case, published articles).
I find the "nested sets" design limiting unless you have complete
foreknowledge of your tree/categories when initially populating the table.
If you have to modify the tree/categories later on, it can get hairy.
Doug
At 02:40 PM 4/20/01 +0200, Tomás GarcíY+0=a Ferrari wrote:
>Hello,
>
>I'm developing a system (with PHP-MySQL) in which I will have different
>articles published. Any given article can correspond to a category (or
>sub-category (or sub-sub-category)). Something like this:
>
>Cat 1
> Sub 1.1
> Sub-Sub 1.1.1
> Sub-Sub 1.1.2
> Sub 1.2
> Sub 1.3
>Cat 2
> Sub 2.1
> Sub 2.2
> Sub-Sub 2.2.1
> Sub-Sub 2.2.2
>[etc]
>
>As per my research on this topic of publishing 'treelike information', there
>are two posibilities:
>
>a) Adjacency list
>
> id | parent | label
> 1 0 Cat 1
> 2 1 Sub 1.1
> 3 2 Sub 1.1.1
> [so on...]
>
>b) Nested sets (as explained in the book JOE CELKO'S SQL FOR SMARTIES
>(Morgan-Kaufmann, 1999, second edition), that I don't have...)
>
> label | lft | rgt
> Cat 1 1 12
> Sub 1.1 2 7
> Sub 1.1.1 3 4
> Sub 1.1.2 5 6
> Sub 1.2 8 9
> Sub 1.3 10 11
> [so on...]
>
>
>Anybody is doing something like this that can share experience with us? I
>can not find a clue yet if one system is better than the other for what I
>need. I realized that the 'Nested Sets' system have a very good approach and
>is very easy to get all the sub (and sub-sub) categories on a given category
>(any record where lft is between lft and rgt:
> SELECT e1.*
> FROM example as e1, example as e2
> WHERE e1.lft BETWEEN e2.lft AND e2.rgt
> AND e2.label = 'Cat 1';
>)
>
>But I'm having problems trying to find -as example- which are all the
>Categories (in the other system are all the records where parent = 0)...
>
>Any ideas?
>
>Regards,
>Tomas Garcia Ferrari
>
>Bigital
>http://bigital.com
>
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