Use a dropdown to dynamic sort records

What i want to do is to have a dropdown that let's users sort a recordset.
For example: newest first, oldest first, Name A-Z, Name Z-A

So my idea was to set a session variable with the values from the dropdown list on change, having the dropdown in a form and submit that form on change.
Example of the dropdown:

Label: Newest first Value: Date DESC (where Date is the column name to sort)

(This works and sets the correct values in the session variable)

Then add a variable called "Sorter" in the recordset query that reads the session variable and use that variable like this: ORDER BY Sorter
expecting the recordset would be sorted by the value in the session variable.

That's where I got stuck now as the sorting doesnt works.

Did I choose a complete wrong approach or did i miss to pay attention to some detail?

Try having a read of this http://www.blazingimages.com/sortable-rows-with-data-assist-version-2 it is a different approach but has been used by a number of other people here to accomplish something similar.

Credit - The solution was created by Neo on this forum and not by me..

Thanks for that hint Daryl

in the meantime I found another interesting solution for this here:
php-sorting-a-list-using-a-drop-down-menu

With little adaptions I got it to work and hope this solution might help some other members too.

Hopefully Webassist might come up with a feature like this, as its specially useful on e-commerce sites

I have used a cookie created by a dropdown list as demonstrated here http://www.tshirt-town.com/sale/clearance-offers.php

The process is that I create a cookie onchange from the select list and submit back to the page via javascript then check the value submitted like so

switch($_COOKIE["sortBy"]) {

    case "newest":

    $orderClause = "tbl_products.tstampinsert DESC, tbl_products.title";

    break;

    case "a-z":

    $orderClause = "tbl_products.title, tbl_products.sortorder";

    break;

    case "z-a":

    $orderClause = "tbl_products.title DESC, tbl_products.sortorder";

    break;

    default:

    // default behaviour

    $orderClause = "tbl_products.sortorder, tbl_products.title";

}

Then you need to add the resulting var into the recordset like so:

AND tbl_subcategories.slug = %s ORDER BY " . $orderClause . "", GetSQLValueString...