Helen (and the others who answered this question):

You say in my code I´m doing this:

start transaction
prepare query if not prepared
run query (i.e. call Open)
start another transaction
do some stuff
post changes
.....

I see your
"start another transaction"

is my
"DataBaseGeneral.StartTransaction;"
(after the Open)

But I don´t see where is your first
"start transaction"
in my code.

If I debug and see DataBaseGeneral.InTransaction before the
DataBaseGeneral.StartTransaction, it is False. So, there is no
Transaction started before the "DataBaseGeneral.StartTransaction;"
instruction.

Even in the Help of Delphi, it is explained that I have to do things
the way I´m doing. That´s why I don´t understand the mistake.

¿When does the first transaction you mention starts?


--- In firebird-support@yahoogroups.com, Helen Borrie <helebor@t...>
wrote:

> At 07:11 PM 15/11/2004 +0000, you wrote:
>
> >Hello to everybody!
> >
> > I´m trying to use InterBase (really it´s FireBird) with

Delphi

> >5 and BDE but I have a problem with Transactions.
> >
> > I want to manage my DataBase editing with explicit

transactions

> >(using DataBase.StartTransaction, Commit and RollBack) but I have
> >conflicts with what I think is an implicit transaction that BDE
> >makes each time I make a Table.Post. In the example code below, I
> >connect to a DataBase, I open a Table, start a transaction, edit a
> >Field, and when I try to Post the record, I get the error "Nested
> >transactions not supported".
>
> Your code:
>
> >var
> > DataBaseGeneral : TDataBase;
> > TablaDeProvincias: TTable;
> >begin
> > DataBaseGeneral:=TDataBase.Create(nil);
> > with DataBaseGeneral do
> > begin
> > DataBaseName:='General';
> > DriverName:='INTRBASE';
> > Params.Values['SERVER NAME']:='General.GDB';
> > Params.Values['USER NAME']:='SYSDBA';
> > Params.Values['PASSWORD']:='masterkey';
> > LoginPrompt:=False;
> > Connected:=True;
> > end;
> >
> > TablaDeProvincias:=TTable.Create(nil);
> > with TablaDeProvincias do
> > begin
> > TableName:='Provinc';
> > IndexFieldNames:='NOMBRE';
> > DataBaseName:=DataBaseGeneral.DataBaseName;
> > Open;
> >
> > DataBaseGeneral.StartTransaction;
> > Edit;
> > TStringField(FieldByName('NOMBRE')).Text:='1'+TStringField
> >(FieldByName('NOMBRE')).Text;
> > Post;
> > DataBaseGeneral.Commit;
> >
> > Close;
> > DataBaseGeneral.Connected:=False;
> > end;
> >end.
>
>
> OK, the cause of this is not understanding that the transaction is

wrapped

> around the entire operation. The sequence of events is this:
>
> start transaction
> prepare query if not prepared
> run query (i.e. call Open)
> do some stuff
> post changes
> run query (i.e. call Refresh)
> do some stuff
> post changes
> ...
> ...
> commit or rollback transaction
>
> What you are trying to do is this:
>
> start transaction
> prepare query if not prepared
> run query (i.e. call Open)
> start another transaction
> do some stuff
> post changes
> .....
>
> Hence, the "nested transaction" error.
>
>
> > I tried to change the settings of BDE with the BDE
> >Administrator but I couldn´t make it work. I tried with

SQLPASSTHRU

> >MODE = SHARED NOAUTOCOMMIT or SHARED AUTOCOMMIT or NOT SHARED, I
> >connected to the DataBase using an Alias or not using an Alias, I
> >tried with SQLQRYMODE null or SERVER, with COMMIT RETAIN FALSE or
> >TRUE, etc. None of this worked!!!
>
> Nothing like this will work to make the database do something it

can't

> do. In Firebird and InterBase, you can't start another

transaction inside

> a transaction.
>
>
> > Does anybody knows what can I do with this?
>
> Well, here are some more problems you have with the BDE that you

are using:

>
> 1. Delphi 5's BDE driver for InterBase doesn't support ODS 10 or

higher

> databases. It is for InterBase 5 (ODS 9) and below.
>
> 2. Delphi 6 shipped with BDE v.5.2, which does have a driver for

ODS 10

> databases. However, the driver is buggy and crags on some of the

data

> types it is meant to support. (At Delphi 6, Borland replaced the

BDE with

> its new DB Express driver layers for client/server databases). You

have to

> buy Delphi 6 to get your hands on the driver -- for a while, you

could buy

> BDE 5.2 from the Borland shop, but it has been off the listings

now for

> about three years.
>
> 3. In the BDE, you can't have multiple concurrent transactions per
> connection in any form (though this isn't the cause of your

problem). To

> get some form of explicit control over transaction aging, you can

set

> COMMIT RETAIN to false in the driver settings. However, the only
> workaround to the default autocommit behaviour is to use cached

updates.

>
> In short, as David said, the BDE is dead. To write Delphi apps

for

> Firebird, you need to use something else for connectivity - IBX

(if you

> want to take the risk of incompatibility), IB Objects, FIBPlus,

UIB. Your

> choices will be somewhat limited by using such an old Delphi. IB

Objects

> supports Delphi 5 but I don't know with any certainty about the

rest...you

> can explore some of the possibilities by going to this link page:
>
> http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_dev_comps
>
> ./heLen