Question

I have a dataset that I need to filter by time. e.g. I want records where the time contained in a TDateTime field is between 6:00 AM and 6:00 PM.

My dataset contains a field named time_of_day, of type TDateTime. The value assigned to the filed is a time, with no date.

I have tried creating the filter string using both the string representation of the time (time_of_day >= '6:00 AM' and time_of_day <= '6:00 PM'), and also using the floating point representation (time_of_day >= 0.25 and time_of_day < 0.75), but neither have worked.

I need to know how to construct the filter string to assign to the TDataSet.Filter property.

Answer 1

I think it might depend on short time format but this works for me using TADODataSet.

ADODataSet1.Filter := 'TimeField = 11:00:00';
ADODataSet1.Filtered := True;

A more full proof solution is to use the OnFilterRecord event instead.

procedure TForm4.ADODataSet1FilterRecord(DataSet: TDataSet; var Accept: Boolean);
begin
    if DataSet.FieldByName('TimeField').AsDateTime = FilterValue then
        Accept := True
    else
        Accept := False
end;

If you need interval it would look like this.

ADODataSet1.Filter := 'TimeField >= 10:00:00 and TimeField < 11:00:00';
ADODataSet1.Filtered := True;

OnFilterRecord

procedure TForm4.ADODataSet1FilterRecord(DataSet: TDataSet; var Accept: Boolean);
begin
    if (DataSet.FieldByName('DateField').AsDateTime >= FromTime) and
         (DataSet.FieldByName('DateField').AsDateTime < ToTime) then
        Accept := True
    else
        Accept := False
end;

If you use AMPM notation you need to enclose the time in '

ADODataSet1.Filter := 'TimeField >= ''10:00 AM'' and TimeField < ''11:00 AM''';
ADODataSet1.Filtered := True;

But I would really recommend the OnFilterRecord instead so you do not have to worry about time formats.