Create  FUNCTION fnAdjustDateTime (@date datetime, @timezone int)

RETURNS datetime 
AS
BEGIN
--
-- declare variables 
--
declare @dst bit
declare @offset int 
declare @result datetime 
--
-- Get the timezone data we will need  
--
if  @timezone = 1 
	Select @offset = -5, @dst = 1 
else if  @timezone = 2 
	Select @offset = -6, @dst = 1 
else if  @timezone = 3 
	Select @offset = -7, @dst = 1 
else if  @timezone = 4 
	Select @offset = -8, @dst = 1 
else if  @timezone = 5 
	Select @offset = -10, @dst = 0 
else if  @timezone = 6 
	Select @offset = -9, @dst = 1 
else if  @timezone = 7 
	Select @offset = -4, @dst = 0 
else if  @timezone = 8 
	Select @offset = -7, @dst = 0 
else if  @timezone = 9 
	Select @offset = -11, @dst = 0 
else 
	Select @offset = -6, @dst = 1 
--
-- Set result now 
--
set @result = DateAdd(hh,@offset,@date) 

return @result 

Create  FUNCTION fnAdjustDateTime_itv (@date datetime, @timezone int)

RETURNS table 
AS
RETURN 
SELECT DateAdd(hh,CASE
                    WHEN  @timezone = 1 THEN -5
                    WHEN  @timezone = 2 THEN -6
                    WHEN  @timezone = 3 THEN -7
                    WHEN  @timezone = 4 THEN -8
                    WHEN  @timezone = 5 THEN -10
                    WHEN  @timezone = 6 THEN -9
                    WHEN  @timezone = 7 THEN -4
                    WHEN  @timezone = 8 THEN -7
                    WHEN  @timezone = 9 THEN -11
                  END,
                    @date) As ResultDate
GO
Create  FUNCTION fnAdjustDateTime (@date datetime, @timezone int)

RETURNS datetime 
AS
BEGIN
--
-- declare variables 
--
declare @dst bit
declare @offset int 
declare @result datetime 
--
-- Get the timezone data we will need  
--
if  @timezone = 1 
	Select @offset = -5, @dst = 1 
else if  @timezone = 2 
	Select @offset = -6, @dst = 1 
else if  @timezone = 3 
	Select @offset = -7, @dst = 1 
else if  @timezone = 4 
	Select @offset = -8, @dst = 1 
else if  @timezone = 5 
	Select @offset = -10, @dst = 0 
else if  @timezone = 6 
	Select @offset = -9, @dst = 1 
else if  @timezone = 7 
	Select @offset = -4, @dst = 0 
else if  @timezone = 8 
	Select @offset = -7, @dst = 0 
else if  @timezone = 9 
	Select @offset = -11, @dst = 0 
else 
	Select @offset = -6, @dst = 1 
--
-- Set result now 
--
set @result = DateAdd(hh,@offset,@date) 

return @result 
END               
GO

select name, dbo.fnAdjustDateTime(create_date,1) from sys.objects

select name, fn.* 
from sys.objects
CROSS APPLY dbo.fnAdjustDateTime_itv(create_date,1) fn