Wed, 18 Jun 1902 08:00:00 GMT
Tricky transaction problem: Catching EDatabaseError from one of several Post within a transaction
On Mon, 10 Nov 1997 17:06:01 +0100, Anders Malmborg
Quote<anders.malmb...@szg.externa.co.at> wrote:
>I believe that this must be a common problem:
>Two Datasets which both have been opened and put in append mode:
>Both Datasets are used in the same Form and should be storeed within one
>transaction.
>This is what I've tried:
>procedure TFrmDetail.BtnOkClick(Sender: TObject);
>begin
> DB.StartTransaction;
> try
> Qry1.Post;
> Qry2.Post;
> DB.Commit;
> ModalResult := mrOk;
> except
> DB.Rollback;
> end;
>Now to the problem:
>If the first Post succeed, and the second not, the Qry1 is no more in
>append mode,
>and by next attempt to call Qry.Post the result will be an exception
>(Dataset is not in Edit or Insert mode).
>The next thing I did try was to re-append the dataset in the except
>section:
> except
> DB.Rollback;
> if (Qry1.State <> dsInsert then
> Qry1.Append;
> if (Qry2.State <> dsInsert then
> Qry2.Append;
>Then the values entered in the Form are cleared, which forces the user
>to reenter all values......
>Would appreciate if someone could give me some hints.
>Anders
try
qry1 post
except
qry1.rollback;
exit;
end; // of try
// here only if first post is ok
try
qry2 post;
except
qry2.rollback;
qry1.rollback;
exit; // or raise ;?
end;
// here only if both posts ok
try
qry1.commit;
qry2.commit;
etc etc
// here
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