How to get order increment id using order id?

Question

How can I get order increment id (like 100000028) with order id (like 28). In sales order page order increment id is like 100000028, but I have order id like 28.

How can I get order increment id by order id? I have tried below

$write = Mage::getSingleton('core/resource')->getConnection('core_read');
$result=$write->query("SELECT entity_id FROM `sales_flat_order` WHERE `increment_id` = 'your increment id' ");
$row = $result->fetch();
echo $row['entity_id'];

Answer 1

$order = Mage::getModel('sales/order')->load($orderid);
$Incrementid = $order->getIncrementId();

Answer 2

The other answers require loading the entire order, which is overkill. You can use this built-in method instead:

Mage::getResourceModel('sales/order')->getIncrementId($orderId)

This will run a simple SELECT query to fetch just that one field.