I believe that if you're exclusion date ranges do not overlap, you may also be able to do it like this:

SELECT OrderID,[MaxNonExclusionDays]=MAX([NonExclusionDays])

FROM (

SELECT OrderID, GapStart=MIN(GapDates), GapEnd=MAX(GapDates)

,[NonExclusionDays]=1+DATEDIFF(day, MIN(GapDates), MAX(GapDates))

FROM (

SELECT OrderID, GapDates

,rn=(ROW_NUMBER() OVER (PARTITION BY OrderID ORDER BY GapDates)-1)/2

FROM (

SELECT OrderID, GapDates

FROM OrderSample a

CROSS APPLY (VALUES (OrderStartDate),(OrderEndDate)) b (GapDates)

UNION ALL

SELECT OrderID, GapDates

FROM ExclusionSample b

CROSS APPLY (

VALUES (ExclusionStartDate-1), (ExclusionEndDate+1)) c(GapDates)

) a

) a

GROUP BY OrderID, rn

) a

GROUP BY OrderID;

I've treated the exclusion days (+ order start/end dates) like a set of islands of date ranges, and then converted them to the gaps, ultimately calculating the MAX gap. Similar to (although not exactly like) what I did in this article: The SQL of Gaps and Islands in Sequences[/url]