What is use of NOLOCK ?

Use of NOLOCK

• NOLOCK is also known and dirty reading or blind reading in SQL Server.
• User can read uncommitted data without any wait by using NOLOCK.
• NOLOCK ignore the any LOCK given to transaction by any SQL user.

Example : 

Code :

BEGIN TRANSACTION 

UPDATE C 

SET C.ContactName='' 

FROM Customers C 

WHERE C.CustomerId = 2

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select * from Customers WHERE CustomerId = 2

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select * from Customers WITH (NOLOCK) WHERE CustomerId = 2