<?php

// Get SQL Resource & Read Connection
$resource = Mage::getSingleton('core/resource');
$readConnection = $resource->getConnection('core_read');
$sales_order_table = $resource->getTableName('sales/order');

// Within Foreach Loop
// Get Order Id from Increment Id (e.g. 100001234)
$order_id = $readConnection
->fetchOne("SELECT `entity_id` FROM `". $sales_order_table ."` WHERE `increment_id` = '100001234'");

?>