-- SQL1 Cost .0625 (22%)
delete externalgraderesults
  from externalgraderesults r
  join dbo.udf_SplitUnlim(@externalresultIdList,',') idlist on r.externalgraderesult_id=idlist.value

-- SQL2 Cost .207 (73.25%)
  delete externalgraderesults
  from externalgraderesults r
  join dbo.udf_Split(@externalresultIdList,',') idlist on r.externalgraderesult_id=idlist.value

-- SQL3 Cost .0133 (4.7%)
  delete 
  from externalgraderesults 
  where externalgraderesult_id in (18,122,131)

-- 7998 bytes max (but faster)
   CREATE FUNCTION dbo.udf_Split (@param varchar(7998)) RETURNS TABLE AS
   RETURN(SELECT substring(',' + @param + ',', Number + 1,
                    charindex(',', ',' + @param + ',', Number + 1) - Number - 1)
                 AS Value
          FROM   Numbers
          WHERE  Number <= len(',' + @param + ',') - 1
            AND  substring(',' + @param + ',', Number, 1) = ',')
 
 
-- Unlimited size
   CREATE FUNCTION dbo.udf_SplitUnlim(@list  ntext,
                                     @delim nchar(1) = N',')
   RETURNS @t TABLE (str varchar(4000),
                     nstr nvarchar(2000)) AS
   BEGIN
      DECLARE @slices TABLE (slice nvarchar(4000) NOT NULL)
      DECLARE @slice nvarchar(4000),
              @textpos int,
              @maxlen int,
              @stoppos int
 
      SELECT @textpos = 1, @maxlen = 4000 - 2
      WHILE datalength(@list) / 2 - (@textpos - 1) >= @maxlen
      BEGIN
         SELECT @slice = substring(@list, @textpos, @maxlen)
         SELECT @stoppos = @maxlen - charindex(@delim, reverse(@slice))
         INSERT @slices (slice) VALUES (@delim + left(@slice, @stoppos) + @delim)
         SELECT @textpos = @textpos - 1 + @stoppos + 2   -- On the other side of the comma.
      END
      INSERT @slices (slice)
          VALUES (@delim + substring(@list, @textpos, @maxlen) + @delim)
 
      INSERT @t (str, nstr)
         SELECT str, str
         FROM   (SELECT str = ltrim(rtrim(substring(s.slice, N.Number + 1,
                        charindex(@delim, s.slice, N.Number + 1) - N.Number - 1)))
                 FROM  Numbers N
                 JOIN  @slices s ON N.Number <= len(s.slice) - 1
                                AND substring(s.slice, N.Number, 1) = @delim) AS x
 
      RETURN
   END

-- Clear cache (for level playing field 
--    - only if wanting to check PHYSICAL performance rather than LOGICAL performance)
-- Do **NOT** run these on a Live server
DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE

-- Comment in the SHOWPLAN to see the Query Plan, OR the STATISTICS to see the logical stats
-- SET SHOWPLAN_TEXT ON
GO
-- SET STATISTICS IO ON; SET STATISTICS TIME ON

-- ... put query here - e.g.:

SELECT * FROM Northwind.dbo.Products

SET STATISTICS IO OFF; SET STATISTICS TIME OFF
GO
SET SET SHOWPLAN_TEXT OFF
GO