select HN
from(
SELECT convert(varchar(10), [IREQ_OD_DT], 120) as OrderDate
      ,[IREQ_PID] as HN
  FROM [view_lab_information_Request]
  where IREQ_INACTIVE = 'N' and IREQ_OD_DT between '@d1' and '@d2'
  ) as x
group by OrderDate, HN
---