Magento根据产品SKU查询产品库存状态

//根据SKU查询产品库存状态
$product = Mage::getModel('catalog/product')->loadByAttribute('sku','HB400');
$stockItem = Mage::getModel('cataloginventory/stock_item')->loadByProduct($product->getId());
$stock = $stockItem->getData('is_in_stock'); //1上架状态,0为下架状态
print_r($stock);exit;