Two True Calendar (independent of @@datefirst)

-- playyuer@Microshaoft.com invent
-- http://www.Microshaoft.com

--2004-09-29 update
--there is NOT any relation with global variable: @@DATEFIRST
-- you can set datefirst any value from 0 to 7 and result can not be affected!


declare @ datetime

set @ = '1995-02-25 11:00:50'
set @ = getdate()

--set datefirst 0
--set datefirst 3
--set datefirst 7


select @ as Date
      ,dateadd(year,datediff(year,0,@),0) as FirstDayOfYear
      ,dateadd(year,1+datediff(year,0,@),0)-1 as LastDayOfYear 
      ,dateadd(quarter,datediff(quarter,0,@),0) as FirstDayOfQuarter
      ,dateadd(quarter,1+datediff(quarter,0,@),0)-1 as LastDayOfQuarter
      ,dateadd(month,datediff(month,0,@),0) as FirstDayOfMonth
      ,dateadd(month,1+datediff(month,0,@),0)-1 as LastDayOfMonth
      ,dateadd(week,datediff(week,0,@),0) as FirstDayOfWeek 
      ,dateadd(week,1+datediff(week,0,@),0)-1 as LastDayOfWeek


select month(min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))) as Month
,datediff(week
          ,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0)))
          ,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))
         ) +1 as WeekOfYear
,datediff(week
          ,dateadd(month,datediff(month,0,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))),0)
          ,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))
         ) +1 as WeekOfMonth
 ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 1
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) 
             else null end as Sunday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 2
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1)) % 7 = 2
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1 
             else null end as Monday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7  = 3
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1)) % 7 = 3
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2)) % 7 = 3
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2 
             else null end as Tuesday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7  = 4
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1)) % 7 = 4
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2)) % 7 = 4
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+3)) % 7 = 4
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+3 
             else null end as Wednesday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 5
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1)) % 7 = 5
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2)) % 7 = 5
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+3)) % 7 = 5
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+3 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+4)) % 7 = 5
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+4 
             else null end as Thursday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 6
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+2) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+3) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+3 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+4) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+4 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+5) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +5)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+5 
             else null end as Friday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+1  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+2) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+3) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+3 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+4) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+4 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+5) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +5)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+5 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+6) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +6)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))+6 
             else null end as Saturday
from
(
select 0 as i
union all
select 1
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select 3
union all
select 4
union all
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select 7
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select 11
) M
,
(
select 0 as i
union all
select 1
union all
select 2
union all
select 3
union all
select 4
union all
select 5
union all
select 6
union all
select 7
union all
select 8
union all
select 9
union all
select 10
union all
select 11
union all
select 12
union all
select 13
union all
select 14
union all
select 15
union all
select 16
union all
select 17
union all
select 18
union all
select 19
union all
select 20
union all
select 21
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select 22
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select 23
union all
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union all
select 26
union all
select 27
union all
select 28
union all
select 29
union all
select 30
) d
where datediff(month,dateadd(year,datediff(year,0,@),0),dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))) = m.i
         

group by datediff(month,0,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))
        ,datediff(week
          ,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0)))
          ,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))
         ) +1 


--==============================================

 

select month(min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))) as Month
--       ,datepart(week,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))) as WeekOfYear
       ,datediff(week
       ,case when (@@datefirst + datepart(weekday,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0))))) % 7 = 1
                  then dateadd(day,-1,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0))))
             else dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0)))
        end     
       ,case when (@@datefirst + datepart(weekday,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))) % 7 = 1
                  then dateadd(day,-1,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))
             else dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))
        end     
        ) +1 as WeekOfYear

       ,datediff(week
       ,case when (@@datefirst + datepart(weekday,dateadd(month,datediff(month,0,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))),0))) % 7 = 1
                  then dateadd(month,datediff(month,0,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))),0) -1
             else dateadd(month,datediff(month,0,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))),0)
        end 
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 1
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))-1
             else min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))
        end     
      )        +1 as WeekOfMonth

       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 2
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) 
             else null end as Monday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 3
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 3
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1 
             else null end as Tuesday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 4
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 4
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+2) % 7 = 4
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2 
             else null end as Wednesday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 5
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 5
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+2) % 7 = 5
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+3) % 7 = 5
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3 
             else null end as Thursday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 6
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+2) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+3) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+4) % 7 = 6
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4 
             else null end as Friday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+2) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+3) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+4) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+5) % 7 = 0
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +5)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +5 
             else null end as Saturday
       ,case when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))) % 7 = 1
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))  
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+1) % 7 = 1
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +1 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+2) % 7 = 1
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +2 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+3) % 7 = 1
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +3 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+4) % 7 = 1
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +4 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+5) % 7 = 1
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +5)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +5 
             when (@@datefirst + datepart(weekday,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))))+6) % 7 = 1
                  and datediff(month,min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))),min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +6)=0
                  then min(dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))) +6 
             else null end as Sunday

from
(
select 0 as i
union all
select 1
union all
select 2
union all
select 3
union all
select 4
union all
select 5
union all
select 6
union all
select 7
union all
select 8
union all
select 9
union all
select 10
union all
select 11
) M
,
(
select 0 as i
union all
select 1
union all
select 2
union all
select 3
union all
select 4
union all
select 5
union all
select 6
union all
select 7
union all
select 8
union all
select 9
union all
select 10
union all
select 11
union all
select 12
union all
select 13
union all
select 14
union all
select 15
union all
select 16
union all
select 17
union all
select 18
union all
select 19
union all
select 20
union all
select 21
union all
select 22
union all
select 23
union all
select 24
union all
select 25
union all
select 26
union all
select 27
union all
select 28
union all
select 29
union all
select 30
) d
where datediff(month,dateadd(year,datediff(year,0,@),0),dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))) = m.i
         
group by datediff(month,0,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))
        ,datediff(week
        ,case when (@@datefirst + datepart(weekday,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0))))) % 7 = 1
                   then dateadd(day,-1,dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0))))
              else dateadd(day,0,datediff(day,0,dateadd(year,datediff(year,0,@),0)))
         end     
        ,case when (@@datefirst + datepart(weekday,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))) % 7 = 1
                   then dateadd(day,-1,dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0))))))
              else dateadd(day,0,datediff(day,0,dateadd(day,d.i,dateadd(month,m.i,dateadd(year,datediff(year,0,@),0)))))
         end) +1