Return unlocked rows in a “select top n” query

Question

I need to have a MsSql database table and another 8 (identical) processes accessing the same table in parallel - making a select top n, processing those n rows, and updating

Answer 1

The most simplest method is to use row locking:

BEGIN TRAN

SELECT *
FROM authors
WITH (HOLDLOCK, ROWLOCK)
WHERE au_id = '274-80-9391'

/* Do all your stuff here while the record is locked */

COMMIT TRAN

But if you are accessing your data and then closing the connection, you won't be able to use this method.

How long will you be needing to lock the rows for? The best way might actually be as you say to place a counter on the rows you select (best done using OUTPUT clause within an UPDATE).