SQL dates range conumdrum

Question

I have a table date range that i'm retrieving with one date specified x_VisitDate

And four variables defined that will use the x_VisitDate

For this instance x_VisitDate = 22 May 2014 the download button should only be available 10 days prior to the given date as at today we are 7 days away.

x_TodaysDate
x_DaysBeForeToDownloadFile = 10
x_AdditionalDayToDownloadFile = 1

x_CanDownloadFile = DateAdd("d", x_DaysBeForeToDownloadFile , x_VisitDate)
x_ExtraCanDownloadFile = DateAdd("d", x_AdditionalDayToDownloadFile, x_VisitDate)

I'm currently writing the following

If x_CanDownloadFile <= x_TodaysDate then

and it's showing the file when the date is set for 21 Oct 2018 (Future) and 23 Feb 2014 (past)

I'm going crazy here...

thanks

Answer 1

Don't use comparisons to constructed limits, but DateDiff for range checks. It's much easier to get right. Demo code:

>> nDaysAvailable = 3
>> dtToday = Date
>> For i = -5 To 0
>>     dtCheck = DateAdd("d", i, dtToday)
>>     nDiff   = DateDiff("d", dtCheck, dtToday)
>>     WScript.Echo dtCheck, nDiff, CStr(nDiff < nDaysAvailable)
>> Next
>>
10.05.2014 5 False
11.05.2014 4 False
12.05.2014 3 False
13.05.2014 2 True
14.05.2014 1 True
15.05.2014 0 True

(german locale)

Answer 2

Maybe I'm confused by your question but can't you just do this?

x_VisitDate = #5/22/14#

If Date >= x_VisitDate - 10 And Date <= x_VisitDate + 1 Then
    ' Show file
End If

Also, you don' t need to use DateDiff() when you're working with days. Just use integer math.