ObjectContext is the object that represents the database connection and its entities.
There may be situations when you may call this more than once in a request to create multiple transactions. I cannot think of a reason right now, but just remember that this acts like a commit transaction as each SaveChanges call will create a new transaction.
However, there are also cases where you may have more than one context to deal with. In that case you may pull data from one database and save them to another database. In this case, you may want to put both contexts’ SaveChanges calls in a TransactionScope to protect this as one atomic transaction.
ObjectContext.SaveChanges Method ()