How to get the closing stock calculation in sql

How to write the sql query calculating the closing stock .

Closing Stock : Opening Stock - other (order_type_desc) 

group by period_key

See Screenshots :

In the above example :

Closing Stock will be : 3375 - (-3498+29821)

There can be other order_type_desc as well . See another example screenshot :

In this example 

Closing Stock : Opening Balance - Sales

How to write a view in SQL SERVER 2005

Thanks,