Playing with DateTime in SQL2005

For a project I'm working on I needed to extract semester and quarter from a date.
This brought me to the idea of storing these values in a table.

The following code sample is a table valued function which generates detailed calendar output.

Create Function [dbo].[DateTimeFunctions.ReturnExtendedCalendar]
  (@TableStartDate DateTime , @TableEndDate DateTime , @FYStart DateTime)
Returns @ExtendedResultSet Table
    ( MonthStart DateTime , MonthEnd DateTime , [Year] Int , [Month] Int , 
     [Quarter] Int , Semester Int , [MonthName] Varchar(20) , [FiscalYear] Int , 
     [FiscalMonth] Int , [FiscalQuarter] Int , FiscalSemester Int)
As
Begin
 Declare @CalendarTable Table 
   ( MonthStart DateTime , MonthEnd DateTime , [Year] Int , [Month] Int , 
     [Quarter] Int , Semester Int , [MonthName] Varchar(20) , [FiscalYear] Int , 
     [FiscalMonth] Int , [FiscalQuarter] Int , FiscalSemester Int)
     
 Declare @FirstDayOfCurrentYear DateTime
 Declare @FiscalStartDiff Int

 Select @FirstDayOfCurrentYear = Cast(Cast(Convert(Varchar(4), DatePart(yyyy ,GetDate())) + '-01-01' As Varchar(20)) As DateTime)

 Select @FiscalStartDiff = DateDiff(mm , @FYStart , @FirstDayOfCurrentYear)

 While @TableStartDate <= @TableEndDate
 Begin
  Insert Into @CalendarTable
    (
     MonthStart , MonthEnd , [Year] , [Month] , [Quarter] , Semester , [MonthName] ,
     [FiscalYear] , [FiscalMonth] , [FiscalQuarter] , FiscalSemester
    )
  Values ( @TableStartDate ,
     DateAdd(ms, -3, DateAdd(mm, DateDiff(m, 0, @TableStartDate) + 1, 0)) ,
     DatePart(yyyy , @TableStartDate ) ,
     DatePart(mm , @TableStartDate ) ,
     DateName(qq , @TableStartDate),
     Case When DatePart(mm , @TableStartDate ) Between 1 and 6 Then 1
       Else 2
     End ,
     DateName(mm , @TableStartDate) ,
     DatePart(yyyy , DateAdd(mm  , @FiscalStartDiff , @TableStartDate )) , 
     DatePart(mm , DateAdd(mm  , @FiscalStartDiff , @TableStartDate )),
     DatePart(qq , DateAdd(mm  , @FiscalStartDiff , @TableStartDate )),
     Case When DatePart(qq , DateAdd(mm  , @FiscalStartDiff , @TableStartDate )) 
         In (1 , 2 )Then 1
       Else 2
     End
    )
     
  Set @TableStartDate = DateAdd(mm , 1 , @TableStartDate)
 End

 Insert @ExtendedResultSet (MonthStart , MonthEnd , [Year] , [Month] , [Quarter] , 
     Semester , [MonthName] , [FiscalYear] , [FiscalMonth] , [FiscalQuarter] , FiscalSemester)
 Select MonthStart , MonthEnd , [Year] , [Month] , [Quarter] , 
     Semester , [MonthName] ,[FiscalYear] , [FiscalMonth] , [FiscalQuarter] , FiscalSemester 
 From @CalendarTable

 Return
End

Execution of the function is as follows :

Set DateFirst 1
Set @TableStartDate = DateAdd(yyyy ,-10 , '2009-01-01')
Set @TableEndDate = DateAdd(yyyy , 0 , '2009-12-31')
Set @FYStart = Convert(DateTime, '2009-04-01')

Select * From [dbo].[DateTimeFunctions.ReturnExtendedCalendar]
         (@TableStartDate , @TableEndDate , @FYStart)