$currentCustomer = Mage::getSingleton('customer/session')->getCustomer();
        $customers = Mage::getResourceModel('customer/customer_collection')
            ->addNameToSelect()
            ->addAttributeToSelect('entity_id')
            ->addAttributeToSelect('email')
            ->addAttributeToSelect('entity_id')
            ->addAttributeToFilter('billing_customer', $currentCustomer->getERPCustomerId())
            ->joinTable(
                array('order' => 'sales_flat_order'), 'customer_email = email',
                array('order_id' => 'order.entity_id'),
                null,
                'left'
            );
        $customers->setOrder('order.created_at', Varien_Data_Collection::SORT_ORDER_DESC);

SELECT `e`.*, `at_prefix`.`value` AS `prefix`, `at_firstname`.`value` AS `firstname`, `at_middlename`.`value` AS `middlename`, `at_lastname`.`value` AS `lastname`, `at_suffix`.`value` AS `suffix`, CONCAT(IF(at_prefix.value IS NOT NULL AND at_prefix.value != '', CONCAT(LTRIM(RTRIM(at_prefix.value)), ' '), ''), LTRIM(RTRIM(at_firstname.value)), ' ', IF(at_middlename.value IS NOT NULL AND at_middlename.value != '', CONCAT(LTRIM(RTRIM(at_middlename.value)), ' '), ''), LTRIM(RTRIM(at_lastname.value)), IF(at_suffix.value IS NOT NULL AND at_suffix.value != '', CONCAT(' ', LTRIM(RTRIM(at_suffix.value))), '')) AS `name`, `at_billing_customer`.`value` AS `billing_customer`, `order`.`entity_id` AS `order_id` FROM `customer_entity` AS `e`
 LEFT JOIN `customer_entity_varchar` AS `at_prefix` ON (`at_prefix`.`entity_id` = `e`.`entity_id`) AND (`at_prefix`.`attribute_id` = '4')
 LEFT JOIN `customer_entity_varchar` AS `at_firstname` ON (`at_firstname`.`entity_id` = `e`.`entity_id`) AND (`at_firstname`.`attribute_id` = '5')
 LEFT JOIN `customer_entity_varchar` AS `at_middlename` ON (`at_middlename`.`entity_id` = `e`.`entity_id`) AND (`at_middlename`.`attribute_id` = '6')
 LEFT JOIN `customer_entity_varchar` AS `at_lastname` ON (`at_lastname`.`entity_id` = `e`.`entity_id`) AND (`at_lastname`.`attribute_id` = '7')
 LEFT JOIN `customer_entity_varchar` AS `at_suffix` ON (`at_suffix`.`entity_id` = `e`.`entity_id`) AND (`at_suffix`.`attribute_id` = '8')
 INNER JOIN `customer_entity_int` AS `at_billing_customer` ON (`at_billing_customer`.`entity_id` = `e`.`entity_id`) AND (`at_billing_customer`.`attribute_id` = '213')
 LEFT JOIN `sales_flat_order` AS `order` ON (order.customer_email =e.email) WHERE (`e`.`entity_type_id` = '1') AND (at_billing_customer.value = '1006')