NOLOCK vs. Transaction Isolation Level

sql sql-server transaction-isolation
Jason picture Jason · Jun 19, 2009 · Viewed 13.4k times · Source

What's the difference between using "SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED" and NOLOCK? Is one better than the other?

Answer

Gavin Miller picture Gavin Miller · Jun 19, 2009

They're the same thing, just scoped differently. NOLOCK is placed on a per table basis and SET Transaction... can be placed as a block.

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