Update Query with Nolock hint

Question

I am trying to put an with(NOLOCK) on an update query:

UPDATE pth_patchLookup with(nolock) SET ScanDateTime = Getdate() WHERE RegID = 312

but I get the following message :

NoLock hint is supported only with Select statement and not with update, insert and delete.

Is there any manner in which I can apply a 'NOLOCK" on this update query ?

Thanks for any help

Answer 1

(NOLOCK) disables shared locks and not exclusive locks. you can use Read Committed isolation level in order to place an exclusive lock on select statements.

SET TRANSACTION ISOLATION LEVEL READ COMMITTED 
UPDATE pth_patchLookup SET ScanDateTime = Getdate() WHERE RegID = 312

Answer 2

And this?

UPDATE TOP (1000) v 
SET idSupervisor = a.supervisor
FROM    dbo.Venda_2014 v WITH ( NOLOCK )
INNER JOIN #supervidores_presentes a WITH (NOLOCK) ON v.IdVendedor = a.vendedor AND v.idEmpresaOriginal = a.empresa
WHERE   IdDistribuidor IN ( 40 )
        AND ISNULL(v.idSupervisor,0) = 0
        AND datAnoMesRef >= '201501' 
Go

Working fine for me.

Answer 3

NOLOCK is a select (only) hint and it's much a bad habit form older programmers since it was almost mandatory in SQL Server 7 but since SQL Server 2000 it's most unnecessary. That hint in particular tell the engine the select can read rows even if it is in the middle of a uncommited transaction. Due to this you can experience dirty or ghost reads.

I strongly suggest you to read about isolation levels to know how to meet your particular system requirements.

Obs: Hints are not commands, you are only suggesting the engine to take a hint but the engine can decide to not use it.