Diffrent Order status and how to change Order status.

Order status

Mage_Sales_Model_Order::STATE_NEW

Mage_Sales_Model_Order::STATE_COMPLETE

Mage_Sales_Model_Order::STATE_PROCESSING

Mage_Sales_Model_Order::STATE_PENDING_PAYMENT

Mage_Sales_Model_Order::STATE_HOLDED

Mage_Sales_Model_Order::STATE_CANCELED

Mage_Sales_Model_Order::STATE_CLOSED

Some time we need to explicitly update the order status. We can change or update the order status as below,

$yourOrder->setState(Mage_Sales_Model_Order::STATE_HOLDED, true);

$yourOrder->save();

It's always good practice to take database backup while doing such operations.