Magento 1 - Often times there is a need to change all Magento Categories from their default setting of 'Is Anchor = No' to 'Is Anchor=Yes'.

change-categories-magento-anchor-set-yes-1-click.php

<?php
/* Making the change to an Anchor Category activates the Layered Navigation, also known as filtered navigation.  If you have multiple Categories this can be a time-consuming task to do manually.  The better way is to use the following code to run through and change all Categories to Anchor in just 1 Click.  *It is always a good idea before making changes to the database that you first create a database backup.  This has become very quick and easy using the Magento Admin.  *To make your backup using Magento Admin, navigate to [System] [Tools] [Backups]. *once there select the option Database Backup (don’t worry it doesn’t take long).  Now that you are ready, create a new file called category-achor-yes.php and place it in the root of your Magento install (where your index.php file is).*/

error_reporting(E_ALL);
ini_set('display_errors', '1');

// Load Up Magento Core
define('MAGENTO', realpath(''));

require_once(MAGENTO . '/app/Mage.php');

$app = Mage::app();

$categories = Mage::getModel('catalog/category')
 ->getCollection()
 ->addAttributeToSelect('*')
 ->addAttributeToFilter('is_anchor', 0)
 ->addAttributeToFilter('entity_id', array("gt" => 1))
 ->setOrder('entity_id')
 ;

foreach($categories as $category) {
 echo $category->getId() . "\t" . $category->getName() . "\n";
 $category->setIsAnchor(1);
 $category->save();
} ?>