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.