How do you make an infinite dynamic menu system?

I have a wiki-type app where an administrator can create pages. Each page must be put into the menu system, which is created on-the-fly by the administrator

Menu Heading
L Subheading
  L Page1

However, there may be more pages for the menu such as:

Menu Heading
L Subheading
  L Page1
  L New Subheading
    L Page2

The menu must be easy to m开发者_开发问答odify and there must be a way to order the headings/subheadings as well as the pages inside.

so basically, an entirely dynamic menu is what i need NO STATIC DATA OF ANY KIND.

I've got a current method that works except i am unable to control page order. If i dont get many responses how to go about it, i will put up my current way of doing things (i just don't want to put ideas into your head, i'm looking for a fresh approach)

Thanks

EDIT: Thank you all for your responses, however, I think the situation is a bit more complex than i can put into words right now. Let me think of a better way to ask my question... I'll repost probably next week

---

Well use a hierarchical schema, add a sort order to each item and that's it.

---

The easiest way to accomplishing a system which has parent -> child -> child... relations would be a tree. Where you use a setup which could look like this:

 id | name      | parent | tree_left | tree_right
----+-----------+--------+-----------+-----------
 0  | root      | NULL   | 0         | 9
 1  | child1    | 0      | 1         | 4
 2  | subchild1 | 1      | 2         | 3
 3  | child2    | 2      | 5         | 8
 4  | subchild2 | 3      | 6         | 7

This would be the database for:

root
|_ child 1
   |_ subchild 1
|_ child 2
   |_ subchild 2

You can get the full structure in 2 easy querys like so:

SELECT * from menu WHERE name = root;
SELECT * FROM menu WHERE tree_left > $root['tree_left'] AND tree_right <  $root['tree_right'] order by tree_left DESC;

When you add children you must enlarge the gap between your parent tree_left and right. you should do this recursively when your in sub, sub items etc. Which can be done in 1 query if i'm not mistaking.

Try and search on the web for more detailed exampled this is a common used tree structure called nested set.

---

A table structured as follows should do it.

MenuItemId | ParentId | Order | Content

TopLevelItem1 (MenuItemId: 1)
 |
 |-> MenuItem2 (ParentId: 1, Order 1)
 |-> MenuItem3 (ParentId: 2, Order 2)

TopLevelItem2 (MenuItemId: 4)
 |
 |-> MenuItem4 (ParentId: 4, Order 1)

Etc..

Inserting items should just require a simple reorder.

---

What you are looking for, is called recursion, here is related question example, also I would recommend to read this article.

---

Exactly what are you wanting to know?

If you are interested in structure, check out this article on hierarchical data on the MySQL website.