TabNum = tr.TabNum,
Dbeg = case when datepart(year,hol.DateBegin) < (select min(nYear) from #TRes) then @DMin else hol.DateBegin end,
Dend = case when datepart(year,hol.DateEnd) > (select max(nYear) from #TRes) then @Dmax else hol.DateEnd end,
SumDays = case when datepart(year,hol.DateBegin) < (select min(nYear) from #TRes) then datediff(day,@DMin,hol.DateEnd+1)
when datepart(year,hol.DateEnd) > (select max(nYear) from #TRes) then datediff(day,hol.DateBegin,@DMax+1)[/FIXED][/FIXED][/FIXED]

WITH [HoliDays] ([From],[To],[TID]) AS (SELECT Convert(Date,[From]),Convert(Date,[To]),TID FROM (VALUES
 ('20111101','20120101',1)
,('20111101','20120601',2)
,('20100301','20100501',3)
)hd([From],[To],[TID])
), [Years] ([Year],[From]) AS (SELECT Year([From]),Convert(Date,[From]) FROM (VALUES
 ('20100101')
,('20110101')
,('20120101')
,('20130101')
)y([From])
)	SELECT	 H.TID
		,Y.[Year]
		,CASE WHEN H.[From] >                Y.[From]  THEN H.[From] ELSE                Y.[From]  END	AS [From]
		,CASE WHEN H.[To]   < DateAdd(Year,1,Y.[From]) THEN H.[To]   ELSE DateAdd(Year,1,Y.[From]) END	AS [To]
	FROM	[HoliDays]	H
	JOIN	[Years]		Y ON Y.[From] >= DateAdd(Year,-1,H.[From])
				 AND Y.[From] <  H.[To]
;

WITH [HoliDays] ([From],[To],[TID]) AS (SELECT Convert(Date,[From]),Convert(Date,[To]),TID FROM (VALUES
 ('20111101','20120101',1)
,('20111101','20120601',2)
,('20100301','20100501',3)
)hd([From],[To],[TID])
), [Years] ([Year],[From],[To]) AS (SELECT Year([From]),Convert(Date,[From]),DateAdd(Year,1,Convert(Date,[From])) FROM (VALUES
 ('20100101')
,('20110101')
,('20120101')
,('20130101')
)y([From])
)	SELECT	 H.TID
		,Y.[Year]
		,CASE WHEN H.[From] > Y.[From] THEN H.[From] ELSE Y.[From] END	AS [From]
		,CASE WHEN H.[To]   < Y.[To]   THEN H.[To]   ELSE Y.[To]   END	AS [To]
	FROM	[HoliDays]	H
	JOIN	[Years]		Y ON Y.[From] >= DateAdd(Year,-1,H.[From])
				 AND Y.[From] <  H.[To]
;

---------Таблица год, сотрудник             + также есть две известные переменные @DMin = '20110101' и @DMax = '20130101', --может они пригодятся
Create table #TRes (nYear int, TabNum varchar(15))

insert #TRes values(2011,'123')
insert #TRes values(2012,'123')
insert #TRes values(2013,'123')

---------Таблица больничных(дата начала, дата окончания, сотрудник)
create table #Ill (DateBegin datetime, DateEnd datetime, TabNum varchar(15))
insert #TRes values('20111204','20120301','123')
insert #TRes values('20110901','20130201','123')
insert #TRes values('20121101','20121201','123')
--Нужно получить  следующий select: Год, дата начала периода отсутствия,дата конца периода отсутствия, кол-во дней --отсутствия. 
select
  Year        = ?
  DBeg       = ?
  DEnd       = ?
  SumDays  = ?
From
  #TRes tr
  Join  #Ill il
    On il.TabNum = tr.TabNum and
         (datepart(year,il.DateBegin) in (select nYear from #TRes) or  datepart(year,il.DateEnd) in (select nYear from #TRes))

create ill

insert #Ill

JOIN #Ill il ON il.TabNum = tr.TabNum AND DATEPART(Year, il.DateBegin) <= tr.nYear AND DATEPART(Year, il.DateEnd) >= tr.nYear

JOIN #Ill il
ON il.TabNum = tr.TabNum
AND tr.nYear >= DATEPART(Year, il.DateBegin)
AND tr.nYear <= DATEPART(Year, il.DateEnd)

WITH [HoliDays] ([From],[To],[TID]) AS (SELECT Convert(Date,[From]),Convert(Date,[To]),TID FROM (VALUES
 ('20111204','20120301',123)
,('20110901','20130201',124)
,('20121101','20121201',125)
)hd([From],[To],[TID])
), [Years] ([Year],[From],[To]) AS (SELECT Year([From]),Convert(Date,[From]),DateAdd(Year,1,Convert(Date,[From])) FROM (VALUES
 ('20100101')
,('20110101')
,('20120101')
,('20130101')
,('20140101')
)y([From])
)	SELECT	 H.TID
		,Y.[Year]
		,X.[From]
		,X.[To]
		,DateDiff(Day,X.[From],X.[To])	AS [Days]
	FROM	[HoliDays]	H
	JOIN	[Years]		Y ON Y.[From] >= DateAdd(Year,-1,H.[From])
				 AND Y.[From] <  H.[To]
	CROSS APPLY (SELECT
		 CASE WHEN H.[From] > Y.[From] THEN H.[From] ELSE Y.[From] END
		,CASE WHEN H.[To]   < Y.[To]   THEN H.[To]   ELSE Y.[To]   END
			)	X([From],[To])

DECLARE @HoliDays TABLE ([From] Date,[To] Date, [TID] Int, PRIMARY KEY ([TID],[From]))
INSERT	@HoliDays VALUES
 ('20111204','20120301',123)
,('20110901','20130201',124)
,('20121101','20121201',125)
DECLARE @Years TABLE ([Year] AS Year([From]),[From] Date PRIMARY KEY, [To] AS DateAdd(Year,1,Convert(Date,[From])))
INSERT	@Years ([From]) VALUES
 ('20100101')
,('20110101')
,('20120101')
,('20130101')
,('20140101')

SELECT	 H.TID
	,Y.[Year]
	,X.[From]
	,X.[To]
	,DateDiff(Day,X.[From],X.[To])	AS [Days]
FROM	@HoliDays	H
JOIN	@Years		Y ON Y.[From] >= DateAdd(Year,-1,H.[From])
			 AND Y.[From] <  H.[To]
CROSS APPLY (SELECT
	 CASE WHEN H.[From] > Y.[From] THEN H.[From] ELSE Y.[From] END
	,CASE WHEN H.[To]   < Y.[To]   THEN H.[To]   ELSE Y.[To]   END
		)	X([From],[To])