new to sql - trying to convert vb function to udf

Hi

I'm an Access/VB coder by experience and trying to move apps to SQL Server 2000.
I have got to grips with the basics of DTS and tables and views and Stored Procedures (to an extent) but now need to upgrade an app that uses a vb function to produce a phased value for a set of budgets.

The VB function looks like this...

----------
Function calcPercentOfBudget(datFromDate As Date, datToDate As Date, iMonth As Integer, cBudget As Currency) As Currency

Dim iDuration As Integer
iDuration = DateDiff("d", datFromDate, datToDate) + 1

' if either date not in current year then 0 (both dates should be in same year)
If Year(datFromDate) <> Year(Now) Or Year(datToDate) <> Year(Now) Then
calcPercentOfBudget = 0
End If

Dim sRatio As Single, idaysInMonth As Integer, idaysInYear As Integer

' if passed month outside of period then 0
If Not (iMonth >= Month(datFromDate) And iMonth <= Month(datToDate)) Then
calcPercentOfBudget = 0
Exit Function
End If

idaysInMonth = daysInMonth(iMonth, Year(Now))


'if from date and to date in same month then 100% of budget
If Month(datFromDate) = Month(datToDate) Then
calcPercentOfBudget = cBudget
Exit Function
End If

' if passed month in From month then ratio of passed month (caters for 1st day of month - 100%)
If Month(datFromDate) = iMonth Then
'calcPercentOfBudget = (idaysInMonth + 1 - Day(datFromDate)) / idaysInYear * cBudget
calcPercentOfBudget = (idaysInMonth + 1 - Day(datFromDate)) / iDuration * cBudget
Exit Function
End If

'if passed month in To month then ratio of passed month (caters for last day of month - 100%)
If Month(datToDate) = iMonth Then
'calcPercentOfBudget = Day(datToDate) / idaysInYear * cBudget
calcPercentOfBudget = Day(datToDate) / iDuration * cBudget
Exit Function
End If

' if passed month within period then 100%
If iMonth > Month(datFromDate) And iMonth < Month(datToDate) Then
'calcPercentOfBudget = idaysInMonth / idaysInYear * cBudget
calcPercentOfBudget = idaysInMonth / iDuration * cBudget
Exit Function
End If

End Function
----------
Function daysInMonth(iMonth As Integer, iYear As Integer) As Integer

Dim datTemp As Date

datTemp = CDate("1/" & CStr(iMonth) & "/" & CStr(iYear))
datTemp = DateAdd("m", 1, datTemp)
datTemp = DateAdd("d", -1, datTemp)

daysInMonth = Day(datTemp)

End Function
----------

I have a UDF function LastDayInMonth to replace the daysInMonth vb function, and that works fine.

However I'm starting to get frustrated in trying to convert the main VB funciton to a UDF function. This is what I have got to, and as you'll see its totally wrong!...

CREATE FUNCTION [dbo].[calcPercentOfBudget] (@.datFrom as datetime, @.datTo as datetime , @.iMonth as int, @.cBudget as money, @.GetDate as datetime)
RETURNS money AS
BEGIN
declare @.iDuration int
declare @.returnvalue money
declare @.sRatio decimal
declare @.iDaysInMonth int

set @.iDuration = datediff(d, @.datFrom, @.datTo)
set @.iDaysinMonth = dbo.LastDayInMonth('1/' + cast(@.iMonth as varchar) + '/' + cast(year(@.getdate) as varchar))

case
when year(@.datFrom) <> year(@.getdate) or year(@.datTo) <> year(@.getdate)
set @.returnvalue = 0
when not(@.iMonth >= Month(@.datFrom) and @.iMonth <= month(@.datTo)
set @.returnvalue 0
when month(@.datFrom) = month(@.datTo)
@.set @.returnvalue = @.cBudget
when month(@.datFrom) = @.iMonth
set @.returnvalue = (@.iDaysInMonth + 1 - day(@.datFrom)) / @.iDuration * @.cBudget
when month(@.datTo) = @.iMonth
set @.returnvalue = Day(datToDate) / iDuration * cBudget
when @.iMonth > month(@.datFrom) and @.iMonth < month(@.datTo)
set @.returnvalue = @.iDaysInMonth / @.iDuration * @.cBudget
end

return @.returnvalue
END

This is my first post to this forum - so any constructive criticism will be welcomed.

Basically, where am I going wrong? - have I got the wrong end of the stick? Have I got the wrong stick? Have I got a stick of dynamite?!

All help greatfully received,
Paul:eek:Case statements work a little differently in T-SQL. Try this:

CREATE FUNCTION [dbo].[calcPercentOfBudget] (@.datFrom as datetime, @.datTo as datetime , @.iMonth as int, @.cBudget as money, @.GetDate as datetime)
RETURNS money AS
BEGIN
declare @.iDuration int
declare @.returnvalue money
declare @.sRatio decimal
declare @.iDaysInMonth int

set @.iDuration = datediff(d, @.datFrom, @.datTo)
set @.iDaysinMonth = dbo.LastDayInMonth('1/' + cast(@.iMonth as varchar) + '/' + cast(year(@.getdate) as varchar))

select @.returnvalue =
case when year(@.datFrom) <> year(@.getdate) or year(@.datTo) <> year(@.getdate) then 0
when not(@.iMonth >= Month(@.datFrom) and @.iMonth <= month(@.datTo) then 0
when month(@.datFrom) = month(@.datTo) then @.cBudget
when month(@.datFrom) = @.iMonth then (@.iDaysInMonth + 1 - day(@.datFrom)) / @.iDuration * @.cBudget
when month(@.datTo) = @.iMonth then Day(datToDate) / iDuration * cBudget
when @.iMonth > month(@.datFrom) and @.iMonth < month(@.datTo) then @.iDaysInMonth / @.iDuration * @.cBudget
end

return @.returnvalue
END

Case in T-SQL returns a value, rather than executes a block of code.|||fantastic, after a couple of other debugs from translation I have a result that works!

Many thanks :)