Magento: Join EAV collection with Flat table

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.

<?php
  $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());

?>