select column magento

我想知道如何选择列。上面你可以看到我想在控制器中写的sql。但我想以正确的方式来做这件事。像magento中的其他sql语句一样。

我尝试添加->列（"o.sku AS sku"），但没有成功。

有什么想法吗？提前感谢！

//sql
$readresult="SELECT o.name AS  'Product', o.sku AS  'SKU', c.entity_id AS  'Order', c.customer_email AS  'Email', c.customer_firstname AS  'Voornaam', c.customer_lastname AS  'Achternaam', c.customer_middlename AS  'Tussenvoegsel', o.product_options AS 'Options', a.telephone AS  'Telefoon', a.postcode AS  'Postcode', a.street AS  'Street', a.city AS  'City', c.increment_id AS 'Bestelnr' FROM magento_sales_flat_order AS c INNER JOIN magento_sales_flat_order_item AS o ON c.entity_id = o.order_id INNER JOIN magento_sales_flat_order_address AS a ON a.parent_id = c.entity_id WHERE o.product_id =".$product." GROUP BY c.entity_id ORDER BY o.sku;";

//THE MAGENTO WAY!
$resource = Mage::getSingleton('core/resource');
$read = $resource->getConnection('core_read');
$o = $resource->getTableName('magento_sales_flat_order');
$o_item = $resource->getTableName('magento_sales_flat_order_item');
$o_address = $resource->getTableName('magento_sales_flat_order_address');
$select = $read->select()->from(array('c'=>$o))
    ->join(array('o'=>$o_item), 'c.entity_id = o.order_id', array(o.sku AS  'SKU'))
    ->join(array('a'=>$o_address), 'a.parent_id = c.entity_id', array())
    ->where('o.product_id', $product)
    ->group('c.entity_id')
    ->order('o.sku');