NOLOCK, READUNCOMMITED 

Specifies that dirty reads are allowed. No shared locks are issued to prevent other transactions from modifying data read by the current transaction, and exclusive locks set by other transactions do not block the current transaction from reading the locked data.

UPDLOCK Specifies that update locks are to be taken and held until the transaction completesAcquiring an update lock does not prevent others from reading the same data, but it does ensure that you're first in line to upgrade your lock to an exclusive lock if you subsequently decide to modify the locked data

* "quote"din Books Online si Inside SQL Server 2000*

Pentru "update" se pot folosi:

         FASTFIRSTROW
        | HOLDLOCK
        | PAGLOCK
        | READCOMMITTED
        | REPEATABLEREAD
        | ROWLOCK
        | SERIALIZABLE
        | TABLOCK
        | TABLOCKX
        | UPDLOCK

 - lista figureaza in BOL SQL 2005 sub numele de "table hint limited". 

* Folosesti cumva alt "isolation level" decat cel "default"?