To Get last hour entry from Table in SQL Server

UPDATE ComplaintDetails
SET
NextCallDate = NULL,
IsAllocatedDateTime = NULL,
Agent_Name = NULL,
Connectedstatus = NULL
Where
uploadnumber = @UNO
AND
Attempt = 0
AND
Status = 'Open'
AND
Connectedstatus = 'open'
AND
isallocatedDatetime < DATEADD(hh,DATEPART(hh,GETDATE())-1,DATEADD(dd,0, DATEDIFF(dd,0,GETDATE())))