Hi Lucas, thanks for your answer.


"In which code AField was NIL? In the one above?"

Yes, the procedure CalculateFields is always receiving Afield = nil, so any
call to this variable raises an access violation. What is wrong?

[]s
Andrei


2012/9/27 Lucas Franzen <luc@...>

> Andrei,
>
> Am 26.09.2012 16:28, schrieb Andrei Luís:
> > Hello folks,
> >
> > I'm dealing with a performance problem for a long time, and I know that
> > part of it has been the calculated fields I'm using.
> >
> > I'm doing them by 'my way', and by this I mean 'any way', not the best.
> >
> > I'm searching about this topic here in the list, and I found something
> like
> > that:
> >
> > 1 procedure Tdm.qrTestCalculateField(Sender: TIB_Statement; ARow:
> TIB_Row;
> > AField: TIB_Column);
> > 2 begin
> > 3 if (AField.FieldName='MYCALC1') then
> > 4 begin
> > 5 AField.AsCurrency := ARow.ByName('FIELD_A').AsCurrency -
> > ARow.ByName('FIELD_B').asCurrency;
> > 6 end;
> > 7
> > 8 if (AField.FieldName='MYCALC2') then
> > 9 begin
> > 10 AField.AsCurrency := ARow.ByName('FIELD_A').AsCurrency +
> > ARow.ByName('FIELD_B').asCurrency;
> > 11 end;
> > 12
> > 13 if (AField.FieldName='MYCALC3') then
> > 14 begin
> > 15 AField.AsCurrency := ARow.ByName('FIELD_A').AsCurrency *
> > ARow.ByName('FIELD_B').asCurrency;
> > 16 end;
> > 17 end;
>
>
> Yes, this is the code as it is used by IBO.
> You can change it to sth. like:
>
> 3 if (AField.FieldName='MYCALC1') then
> 4 begin
> 5 AField.AsCurrency := ARow.ByName('FIELD_A').AsCurrency -
> ARow.ByName('FIELD_B').asCurrency;
> 6 end // remove ";"
> 7
> 8 else if (AField.FieldName='MYCALC2') then // add ELSE!
>
> since it's pretty useless to ask for field MYCALC2 when it was already
> MYCALC1.
>
> >
> >
> > My questions:
> > 1 - Is this the best way to use calculated fields in IBO? I mean, is it
> the
> > fastest way thinking about performance?
>
> With calculated fields I don't know neither another nor a faster way.
>
> > 2 - I tried this code, but AField is always NIL!??? So if I run it like
> > that, I get an access violation exception at line 3. So I tried to
> isolate
> > this with a 'If AField = nil then exit', but every time the event is
> > called, AField is nil, then nothing is calculated.
>
> In which code AField was NIL?
> In the one above?
>
> > 3 - How about the code below? This is what I'm doing today:
>
> This one should rather produce access violations than the one above
> since it's not testing for aRow being assigned.
>
> > 1 procedure Tdm.qrTestCalculateField(Sender: TIB_Statement; ARow:
> > TIB_Row; AField: TIB_Column);
> > 2 begin
> > 3 ARow.ByName('MYCALC1').asCurrency :=
> > ARow.ByName('FIELD_A').AsCurrency - ARow.ByName('FIELD_B').asCurrency;
> > 4 ARow.ByName('MYCALC1').asCurrency :=
> > ARow.ByName('FIELD_A').AsCurrency + ARow.ByName('FIELD_B').asCurrency;
> > 5 ARow.ByName('MYCALC1').asCurrency :=
> > ARow.ByName('FIELD_A').AsCurrency * ARow.ByName('FIELD_B').asCurrency;
> > 6 end;
>
> Luc.
>
>
>
> ------------------------------------
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