Magento – Is it possible to sort Magento sub categories by alphabetical order by default? NOT with thesql sporadically

If you have only one language so there is only one way to sort categories alphabetically I recommend changing their position so you will let Magento do its magic.
If you have more than one language, or you need the categories sorted alphabetically only on frontend ignore this answer.

Here is a small script that sets the category position.
$parentId - it the category id for which we sort the children
$conn - is a database connection because there is no need to involve the full internal API for changing only one field. we can run queries directly on the DB. I know that this is a big 'NO-NO' but in this case it works.

function orderCategories($parentId, $conn){
    //The position field is in the main category table
    //add prefix if you have one
    $table = 'catalog_category_entity';
    //get the children for a specific category id
    $collection = Mage::getModel('catalog/category')->getCollection()
        ->addAttributeToSelect('name')
        ->addFieldToFilter('parent_id', $parentId);
    $categories = array();
    foreach ($collection as $category){
        //in case there are 2 categories with the same name we shouldn't skip them
        //but there shouldn't be
        $categories[$category->getName().'_'.$category->getId()] = $category->getId();
    }
    //sort categories by name
    ksort($categories);
    //set their position
    $position = 1;
    foreach ($categories as $name=>$id){
        $q = "UPDATE {$table} SET `position` = {$position} where `entity_id` = {$id}";
        $conn->query($q);
        $position++;
        //sort the current category children by calling the same function recursively
        orderCategories($id, $conn);
    }
}

Now that we have the function we just need to run it.
For this create a file. Let's call it categories.php and place it in the root of your Magento instance. The file should contain this:

<?php
//set error reporting to see if something is wrong.
error_reporting(E_ALL | E_STRICT);
ini_set('display_errors', 1);
define('MAGENTO_ROOT', getcwd());
$mageFilename = MAGENTO_ROOT . '/app/Mage.php';
require_once $mageFilename;
//set developer mode for additional debug functionality
Mage::setIsDeveloperMode(true);
//instantiate Mage_Core_Model_App;
Mage::app();
//set the initial parameters for the function
$root = 1;
$conn = Mage::getSingleton('core/resource')->getConnection('core_write');
//sort categories
orderCategories($root, $conn);

You can add the function defined above in the same file below these lines

Now you just need to call in the browser mysite.com/categories.php.
Clear the cache and reindex the category flat data and you are done.
Just to make sure, backup your database before trying it.

you cannot modify the attribute created_at in the backend.
So you need to create a module that just activates the created_at attribute for sorting.

For this you will need the following files:

app/etc/modules/[Namespace]_[Module].xml - the declaration file

<?xml version="1.0"?>
<config>
    <modules>
        <[Namespace]_[Module]>
            <codePool>local</codePool>
            <active>true</active>
            <depends>
                <Mage_Catalog />
            </depends>
        </[Namespace]_[Module]>
    </modules>
</config>

app/code/local/[Namespace]/[Module]/etc/config.xml - the configuration file

<?xml version="1.0"?>
<config>
    <modules>
        <[Namespace]_[Module]>
            <version>1.0.0</version>
        </[Namespace]_[Module]>
    </modules>
    <global>
        <resources>
            <[namespace]_[module]_setup>
                <setup>
                    <module>[Namespace]_[Module]</module>
                    <class>Mage_Catalog_Model_Resource_Setup</class> <!-- Make sure you use this class for setup -->
                </setup>
            </[namespace]_[module]_setup>
        </resources>
    </global>
</config>

app/code/local/[Namespace]/[Module]/sql/[namespace]_[module]_setup/install-1.0.0.php - the install script

<?php
$this->updateAttribute('catalog_product', 'created_at', 'frontend_label', 'Date Added'); //Set a label to the attribute because by default it does not have one
$this->updateAttribute('catalog_product', 'created_at', 'used_for_sort_by', '1'); //mark the attribute as used for sorting.

Clear the cache and refresh any page. Now you should have the Date Added (created_at) attribute available for sorting in any category.