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  • Status: Solved
  • Priority: Medium
  • Security: Public
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Comparing dates in Delphi. Greater than/ Less than

I have a TcxGrid and on a DB column on validate i run the following code.

  
sDate := VarToStr(DisplayValue);
  sNew  := (DateToStr(Now + 49));
  if (sDate < sNew) then begin 
    MessageDlg('Please enter a Committed Delivery Date that is 7 weeks from today.', mtError, [mbOK], 0);
    gvMasterChangeLogCommittedDelivery.DataBinding.Field.Clear;
    gvMasterChangeLog.DataController.DataSet.FieldValues['PlannedInstall']  := sInstall; //INSTALL
    gvMasterChangeLogCommittedDelivery.Focused;
    exit;
  end;

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the problem is that if someone picks a date in the following month (October, greater than September) it still runs the error message.
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Bianca
Asked:
Bianca
  • 2
1 Solution
 
SteveBayCommented:
Why are you comparing them as strings?

It would be more accurate to compare two dates (which are double values) rather than dates that have been converted to strings.

'10' < '9' = True // String comparison
10 < 9 = False // Date (numeric) comparison.
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BiancaAuthor Commented:
I'm not sure how to do that. How do i take the selected date and compare it to today + 49 (Seven weeks)?
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SteveBayCommented:
Assuming that "DisplayValue" is a Variant it would look something like this:
procedure TForm1.Button1Click(Sender: TObject);
var  DisplayValue : Variant;
     dDate, dNew : TDate;
begin
     DisplayValue := DateTimePicker1.DateTime;
     dDate := VarToDateTime(DisplayValue);
     dNew := Now + 49;
     if dDate < dNew then
          ShowMessage('Date is too soon')
     else
          ShowMessage('Date is Acceptable');
end;

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