join EAV collection with Flat table Magento

Joining tables in Magento when it comes to EAV with Flat table is quite complicated. Consider you want to join sales_flat_order table with customer EAV tables to get Customer’s firstname and lastname, it becomes difficult as customer’s name comes from customer_entity_varchar table.

Below code will join sales order flat table with customer EAV to get customer’s full name in the collection along with all the order details.

$coll = Mage::getModel('sales/order')->getCollection();
$fn = Mage::getModel('eav/entity_attribute')->loadByCode('1', 'firstname');
$ln = Mage::getModel('eav/entity_attribute')->loadByCode('1', 'lastname');
$coll->getSelect()
    ->join(array('ce1' => 'customer_entity_varchar'), 'ce1.entity_id=main_table.customer_id', array('firstname' => 'value'))
    ->where('ce1.attribute_id='.$fn->getAttributeId())
    ->join(array('ce2' => 'customer_entity_varchar'), 'ce2.entity_id=main_table.customer_id', array('lastname' => 'value'))
    ->where('ce2.attribute_id='.$ln->getAttributeId())
    ->columns(new Zend_Db_Expr("CONCAT(`ce1`.`value`, ' ',`ce2`.`value`) AS fullname"));
print_r($coll->getData());

Let me know your comment if you have any query