Ordering Links Taken from a DatabaseBy Bob
I set up the admissions site at my college as what I like to think of as a web application as opposed to a bunch of web pages. It is an ASP application that pulls all of its information- menu titles and links, sub menu titles and links, and page content- from a database. The information retrieved from the database is determined by parameters passed through the query string. All of the menu links on the page link back to this main page with a query string. For example, when you click on a main menu link on the nav. bar, the page reloads with the main menu item's corresponding content and all of the sub menu links listed under the main menu link. If you are interested in how the tables are set up or the links are generated, please email me.
There are administration pages that allow non-computer savvy people to add and remove menu items and content to and from the database, thus modifying the web site. These people were not satisfied with the menu items simply being displayed in alphabetical order. They wanted to come up with their own order.
I started out by adding an additional numerical field to the menu tables
in the database called
zorder. A text box corresponding to this field
was added to the admin pages and the main page was modified so that
when it loaded the menu links, it sorted them by their
zorder field first
and then their title field, whereas before they were sorted only by the
title field. If the user left the
zorder field blank, I could have done
one of two things: give that item the next available
making it the last in the list; or give all items with blank
values the same maximum
zorder value thus making them all be displayed
alphabetically at the end.
I would have liked to just leave it at this, but I foresaw two problems:
these same non-computer savvy people having problems with the idea of
zorder field on the admin pages, and I would get tired of
manually updating all of the
zorder values every time I wanted to insert
a menu link.
First of all, I labeled the
zorder field on the entry and edit forms
Menu Position and I used a drop down box of numbers to prevent users
from entering erroneous values. The drop down box contained the numbers
from 1 to the maximum
zorder number and defaulted to the last possible
number (1 plus the maximum
zorder numer) when they were adding a new
item and to the existing
zorder number when they were modifying an item.
If the user enters a
zorder number that is already in use, you will have
to update the following
zorder numbers accordingly. Given that
selectedzorder refers to the
zorder number (menu position) that the
user selected for the current record then the following SQL query will
perform the required update on the following menu records:
To retrieve the maximum
zorder value for use in your drop down box you
could use this query:
The same rules apply to the sub menu table with obvious modifications.