Read Uncommitted Isolation

If you set the Read Uncommitted mode for a session, no isolation is provided to the SELECT queries in that session. A transaction that is running with this isolation level is not immune to dirty reads, nonrepeatable reads, or phantom reads.

To set the Read Uncommitted mode for a session, you run the following statements from the client:

T-SQL—Use SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED.

ODBC—Use the function call SQLSetConnectAttr with Attribute set to SQL_ATTR_TXN_ISOLATION and ValuePtr set to SQL_TXN_READ_UNCOMMITTED.

OLE DB—Use the function call ITransactionLocal::StartTransaction with the isoLevel set to ISOLATIONLEVEL_READUNCOMMITTED.

ADO—Set the IsolationLevel property of the Connection object ...

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