Flush magento 1.9 database

script.php

<?php

include_once('app/Mage.php');

// customers
function destroyAllCustomers() {
    function destroyCustomer($customerId) {
        Mage::getModel("customer/customer")->load($customerId)->delete();
    }

    $customers = Mage::getModel('customer/customer')->getCollection();

    foreach ($customers as $customer) {
        destroyCustomer($customer->getId());
    }
}

// products
function destroyAllProducts() {
    function destroyProduct($productId) {
        Mage::getModel('catalog/product')->load($productId)->delete();
    }

    $products = Mage::getResourceModel('catalog/product_collection');

    foreach ($products as $product) {
        destroyProduct($product->getId());
    }
}

// product categories
function destroyAllProductCategories() {
    function destroyProductCategory($categoryId) {
        Mage::getModel('catalog/category')->load($categoryId)->delete();
    }  

    $productCategories = Mage::getResourceModel('catalog/category_collection');

    foreach ($productCategories as $productCategory) {
        destroyProductCategory($productCategory->getId());
    }
}

// sale orders
function destroyAllSaleOrders() {
    function destroySaleOrder($saleOrderId) {
        Mage::getModel('sales/order')->load($saleOrderId)->delete();
    }

    $saleOrders = Mage::getModel('sales/order')->getCollection();

    foreach ($saleOrders as $saleOrder) {
        destroySaleOrder($saleOrder->getId());
    }
}

Mage::app();
Mage::register('isSecureArea', TRUE);
destroyAllSaleOrders();
destroyAllCustomers();
destroyAllProducts();
destroyAllProductCategories();
Mage::unregister('isSecureArea');

die('done');