There are two possibilties, when the OnDataChange-Event fires:
1) a field has been changed
2) when you scroll in the dataset
therefore try this way

if Assigned(Field) then
begin
// field has been changed
if (field.fieldname='XX') then ...
end
// scroll
else
do something, if you want


Guido.

Magnus Johansson wrote:

> Hi list.
>
> I'm getting AV when using
>
> if (Field.FieldName = 'XX') then begin ...
>
> in OnDataChange because Field = nil.
> Is there any way to know which particular field that is changed and triggering the event?
> When field XX is changed I wan't to update SQLWhere to filter a "lookup"-Query that is connected with keysource to another query.
> Maybe one should use params instead? If so, is there any difference in performance?
>
> Regards, Magnus.
> (D5, IBO 3.6.Ce)
>
>
> [Non-text portions of this message have been removed]
>