Dirty Read on SQL Server
From this documentation - SET TRANSACTION ISOLATION LEVEL - under REMARKS


  Only one of the isolation level options can be set at a time, and it
  remains set for that connection until it is explicitly changed. All
  read operations performed within the transaction operate under the
  rules for the specified isolation level unless a table hint in the
  FROM clause of a statement specifies different locking or versioning
  behavior for a table.


You can use this query to determine the isolation level you are currently at:

SELECT CASE transaction_isolation_level 
WHEN 0 THEN 'Unspecified' 
WHEN 1 THEN 'ReadUncommitted' 
WHEN 2 THEN 'ReadCommitted' 
WHEN 3 THEN 'Repeatable' 
WHEN 4 THEN 'Serializable' 
WHEN 5 THEN 'Snapshot' END AS TRANSACTION_ISOLATION_LEVEL 
FROM sys.dm_exec_sessions 
where session_id = @@SPID