Get the highest updated ID of a multi row update - sql-server

Question

Update: I am using Sql Server 2008 R2.
I am going to update a large number of rows and to avoid unnecessary locking I will do this in matches of around a thousand lines per update.
Using SET ROWCOUND I can limit the update to 1000 lines and using WHERE ID > x I can set which batch it should run.
But for this to work I need to know the highest ID from the just processed batch.
I could user OUTPUTto return all affected ID's and find the highest one on code but I would like to be able to return just the highest ID.
I tried this
SELECT MAX(id)
FROM (
UPDATE mytable
SET maxvalue = (SELECT MAX(salesvalue) FROM sales WHERE cid = t.id GROUP BY cid)
OUTPUT inserted.id
FROM mytable t
WHERE au.userid > 0
) updates(id)
But it gives me this error
A nested INSERT, UPDATE, DELETE, or MERGE statement is not allowed in a SELECT statement that is not the immediate source of rows for an INSERT statement.
BUT if I try to insert the result into a table directly it is valid
CREATE TABLE #temp(id int)
INSERT INTO #temp
SELECT MAX(id)
FROM (
UPDATE mytable
SET maxvalue = (SELECT MAX(salesvalue) FROM sales WHERE cid = t.id GROUP BY cid)
OUTPUT inserted.id
FROM mytable t
WHERE au.userid > 0
) updates(id)
drop table #temp
Is there any workaround to this and can anyone explain why I can insert the result into a table but not just return the result?

Answer 1

DO NOT USE SET ROWCOUNT for this (or, at all), as BOL says:
Using SET ROWCOUNT will not affect DELETE, INSERT, and
UPDATE statements in the next release of SQL Server!
Do not use SET
ROWCOUNT with DELETE, INSERT, and UPDATE statements in new development
work, and plan to modify applications that currently use it. Also, for
DELETE, INSERT, and UPDATE statements that currently use SET ROWCOUNT,
we recommend that you rewrite them to use the TOP syntax.
You could do it with a table variable, too:
DECLARE #Log TABLE (id INT NOT NULL);
UPDATE TOP 1000 mytable
SET maxvalue = (SELECT MAX(salesvalue) FROM sales WHERE cid = t.id GROUP BY cid)
OUTPUT inserted.id INTO #Log
FROM mytable t
WHERE au.userid > 0
SELECT maxid = MAX(id)
FROM #Log