;with Data(ID)
as
(
	select 100 union all
	select 200 union all
	select 300 union all
	select 400 union all
	select 500
)

select *
from Data d
outer apply
(
	select top 1 ID from Data d2 where d2.ID < d.ID order by ID desc
) x

--===== Create the test data.
     -- This is NOT a part of the solution.
     -- We're just building the test data table
     -- to look as expected.
 SELECT ID = Number 
   INTO #YourTable
   FROM master.dbo.spt_values
  WHERE Type = 'P'
    AND Number %100 = 0
;
--===== Add the expected clustered index.
     -- This is also NOT a part of the solution.
     -- We're just building the test data table
     -- to look as expected.
  ALTER TABLE #YourTable
    ADD PRIMARY KEY CLUSTERED (ID)
;
--===== This is the classic solution that will work on all versions of
     -- SQL Server and is very fast in the presence of the correct index.
 SELECT ID, MID = (SELECT TOP 1 ID FROM #YourTable t2 WHERE t2.ID < t1.ID ORDER BY t1.ID DESC)
   FROM #YourTable t1
;

 
         MID=(CASE WHEN ID-100=0 THEN NULL 
                  ELSE ID-100 END
                  )