having trouble getting sales for quarter

Question

I'm trying to pull out the sales totals for quarter 1. I can't seem to get this to work. Any suggestions?

$total = 0;
$orders = Mage::getModel('sales_order/collection')
   ->addAttributeToSelect('*')
   ->addAttributeToFilter('created_at', array(
      'from' => '2012-01-01',
      'to' => '2012-03-31'));
foreach ($orders as $order) {
   $total += $order->getGrandTotal();
}
echo $total;

Answer 1

You're not getting the collection properly. There are multiple ways to do this, looks like you might've combined a couple methods:

1. Mage::getModel('sales/order')->getCollection() or
2. Mage::getResourceModel('sales/order_collection')

However, if all you really want is to sum the single attribute grand_total it is way more efficient to build your own query rather that loading the entire sales order collection:

$db = Mage::getSingleton('core/resource')->getConnection('core_read');
$salesTable = Mage::getSingleton('core/resource')->getTableName('sales/order');
list($total) = $db->fetchCol(
    $db->select()
       ->from($salesTable, array('grand_total' => 'SUM(grand_total)'))
       ->where('DATE(created_at) >= ?', '2012-01-01')
       ->where('DATE(created_at) <= ?', '2012-03-31')
);
echo $total;