Magento Export configurable products ready for MAGMI import (columns sku, configurable_attributes, simples_skus)

exportConfigurables.php

<?php
/**
 * This file should be placed into the `shell` folder
 * You should need a table in your database with fields:
 * - sku
 * - configurable_attributes
 * - simples_skus
 *
 */
require_once 'abstract.php';

/**
 * Magento Category Export Shell Script
 *
 * @category    Mage
 * @package     Mage_Shell
 * @author      Magento Core Team <core@magentocommerce.com>
 */
class Mage_Shell_ExportConfigurable extends Mage_Shell_Abstract
{
    protected $connection;

    /**
     * Run script
     *
     */
    public function run()
    {
      $mysqli = new mysqli('localhost', 'root', '', 'temp_delete');
      $collectionConfigurable = Mage::getResourceModel('catalog/product_collection')->addAttributeToFilter('type_id', array('eq' => 'configurable'));
      foreach ($collectionConfigurable as $_configurableproduct) {
        $product = Mage::getModel('catalog/product')->load($_configurableproduct->getId());
        $productAttributeOptions = $product->getTypeInstance(true)->getConfigurableAttributesAsArray($product);
        $sku = $product->getSku();
        $attributes = array();
        foreach ($productAttributeOptions as $productAttribute) {
          $attributes[] = $productAttribute['attribute_code'];
        }

        $configurable= Mage::getModel('catalog/product_type_configurable')->setProduct($product);
        $simpleCollection = $configurable->getUsedProductCollection()->addAttributeToSelect('*')->addFilterByRequiredOptions();

        $simpleSkus = array();

        foreach($simpleCollection as $simpleProduct){
          $simpleSkus[] = $simpleProduct->getSku();
        }

        $attrsString = implode(',', $attributes);
        $skusString = implode(',', $simpleSkus);

        $sku = $mysqli->real_escape_string($sku);

        $query = "INSERT INTO configurables (sku,configurable_attributes,simples_skus) VALUES ('{$sku}','{$attrsString}','$skusString')";

        if (!$mysqli->query($query)) {
          echo $mysqli->error;
          die;
        }
      }
    }

    /**
     * Retrieve Usage Help Message
     *
     */
    public function usageHelp()
    {
        return <<<USAGE
Usage:  php exportConfigurables.php

  help                        This help

USAGE;
    }
}

$shell = new Mage_Shell_ExportConfigurable();
$shell->run();