How to use Nolock in SQL server

Question

How and why to use Nolock in SQL server with example.

Puneet Kankar · Accepted Answer

Hi Chittaranjan,   Nolock is the equivalent of using Read UNCOMMITTED as a transaction isolation level. So, you stand the risk of reading an uncommitted row that is subsequently rolled back, i.e. data that never made it into the database. So, while it can prevent reads being deadlocked by other operations, it comes with a risk.   For better understanding, you watch and go through below links.   https://www.youtube.com/watch?v=VfuhGS79gnQ     https://www.mssqltips.com/sqlservertip/2470/understanding-the-sql-server-nolock-hint/    https://www.sqlshack.com/understanding-impact-clr-strict-security-configuration-setting-sql-server-2017/

Guest User · Answer

https://www.mssqltips.com/sqlservertip/2470/understanding-the-sql-server-nolock-hint/

Salman Beg · Answer

Follow these links,   https://www.mssqltips.com/sqlservertip/2470/understanding-the-sql-server-nolock-hint/   https://sqlserverplanet.com/tsql/using-with-nolock   Thanks.

Jefferson S. Motta · Answer

Select * From Customers WITH(NOLOCK) LEFT JOIN Products WITH(NOLOCK) ON Products.customerId=Customers.id;   WITH(NOLOCK) returns dirty data, I use for fixed data tables, like TypeTable of something or cities that not change constantly.

Dipa Mehta · Answer

The WITH (NOLOCK) table hint is used to override the default transaction isolation level of the table or the tables within the view in a specific query, by allowing the user to retrieve the data without being affected by the locks, on the requested data, due to another process that is changing it.     https://www.sqlshack.com/understanding-impact-clr-strict-security-configuration-setting-sql-server-2017/   check this link too.