Converting Cursor based Duplication Procedure to SQL - sql

Question

I am trying to take a stored procedure that copies parent/child/grandchild rows into the same tables with a new unique identifier. The purpose of this is to produce a duplicate 'Order' with 'Order Lines' and 'Order Line Attributes'. The procedure currently in place is done using cursors, and I'd like to try and create a set based version.
One issue I've hit early on, is that automatic numbering in a human friendly format is done in a stored procedure.
DECLARE #sales_order_id nvarchar(50)
EXEC GetAutoNumber 'Order', #sales_order_id output
The execution is done within the cursor as it loops through the order Lines of a single order. Is there any way to call this on the fly? I thought of using a table value function but can't because the stored procedure updates the autonumber table to create the new value.
Ideally I would want to craft an insert statement that automatically retrieves/updates the AutoNumber that could be done across multiple rows simulatenously, for example:
INSERT INTO ORDER (
OrderId, -- Guid
OrderNumber, -- Human Friendly value that needs Autoincremented
...
)
SELECT
NEWID(),
???
FROM ORDER
WHERE OrderId = #OrderToBeCopied
I'm using SQL Server 2008, any suggestions?
EDIT: One reason that an identity column would not work is that the table these autonumbers are being stored in serves multiple entities and their prefixes. For instance, here is the DDL for the autonumber table:
CREATE TABLE [dbo].[pt_autonumber_settings](
[autonumber_id] [uniqueidentifier] NULL,
[autonumber_prefix] [nvarchar](10) NULL,
[autonumber_type] [nvarchar](50) NULL,
[changed_by] [nvarchar](30) NOT NULL,
[change_date] [datetime] NOT NULL,
[origin_by] [nvarchar](30) NOT NULL,
[origin_date] [datetime] NOT NULL,
[autonumber_currentvalue] [nvarchar](50) NULL
) ON [PRIMARY]
So the end result from the stored procedure is the newest autonumber_id for a certain autonumber_type, and it also retrieves the autonumber_prefix and concatenates the two together.

Answer 1

Is there some reason you can't use an IDENTITY column?

Answer 2

Please read edit below as my original answer isn't satisfactory
I'm not entirely sure how your OrderNumber is incremented but you could certainly use ROW_NUMBER() for this. Check out the MSDN doco on it
Assuming you just wanted a number allocated to each Order Id, then you'd have something like;
SELECT NEWID(),
ROW_NUMBER() OVER (ORDER BY <whatever column you need to order by to make the row number meaningful>) As MyFriendlyId
FROM ORDER
WHERE OrderId = #OrderToBeCopied
If it needs to have some sort of initial seed value, then you can always use
ROW_NUMBER() OVER (ORDER BY <whatever column you need to order by to make the row number meaningful>) + 1000 As MyFriendlyId -- or whatever your seed value should be
Edit:
I just re-read your question, and I suspect you wish to make OrderNumber to be unique across all records. I misread it initially to be something like an incremental line number to detail line items of the OrderId.
My solution in this case won't be any good, and I'd more inclined to go with the other answer suggested about having an identity column.
You could potentially select MAX(OrderNumber) at the beginning and then use that in conjunction with ROW_NUMBER but this is dangerous as it is likely to be a dirty read and won't guarantee uniquness (if someone performs a concurrent insert). If you did have a unique constraint and there was a concurrent insert while both reading the same MAX(OrderNumber) then you are likely to face unique constraint violations...so yeah...why can't you use an identity column :)