Hi,
Thanks for all the tips! They will be used for sure.
However, I am still at a loss as to how the generator can increment by 3
with a single call to the IBOQuery. It should only increment by 1. I have
tried several different combinations of components and the result is always
the same. This is not coincidence.
The only time it works is if you use the IBODatabase to control the
transaction (and use the default trns) or to not explicitly do a
transaction.

Thanks,
- René

----- Original Message -----
From: "Helen Borrie" <helebor@...>
To: <IBObjects@yahoogroups.com>
Sent: Tuesday, December 30, 2003 5:43 AM
Subject: Re: [IBO] generator increments by 3


> At 11:03 PM 29/12/2003 -0700, you wrote:
> >Hi,
> > I have a TIBOQuery with the following sql:
> > select gen_id(lotidgen, 1) from rdb$database
> >
> >Am using the following components in an simple test application:
> >
> > IBOQuery1: TIBOQuery;
> > IBOTransaction1: TIBOTransaction;
> > IBOQuery1GEN_ID: TLargeintField;
> > Button1: TButton;
> > Label1: TLabel;
> > IB_Connection1: TIB_Connection;
> > IB_Session1: TIB_Session;
> >
> >I have a button event with the code:
> >
> >var
> > num : int64;
> >begin
> >if IBOQuery1.active then
> > IBOQuery1.active := false;
> > IBOTransaction1.StartTransaction;
> > try
> > IBOQuery1.active := true;
> > num := IBOQuery1GEN_ID.aslargeint;
> > label1.caption := inttostr(num);
> > except
> > IBOTransaction1.Rollback;
> > raise;
> > end;
> > IBOTransaction1.Commit;
> >end;
> >
> >When I run the program, the generator is incremented by 3 each time I
click
> >the button. Why is this?
> >If I use a TIBODatabase and use it to control the transaction, then the
> >generator increments properly (ie, by one each time).
>
> I suspect this is coincidence.
>
> Every time you set this query active, the generator will fire. You can't
> rollback a number-generation - once it happens, it is done "for
> good". Generators fire independently of any transaction. Each time you
> "open" that query, you will return the next number of the series - hence
> the behaviour you are seeing. Each click of the button increments the
> generator.
>
> Don't use the IBOQuery you have shown us to get the new value of the
> generator. It does exactly what you don't want. Use the GeneratorLinks
> property of the query that needs the value, e.g. qryYourTable. The entry
> should look something like this (no spaces in it):
>
> idfield=lotidgen
>
> >Should a TIB_Connection component not be used with the Tdataset
compatible
> >components?
>
> You can use a TIB_Connection with the TDataset-compatible
> components. IBODatabase can be more useful if you are converting a BDE
> application, as it has some VCL compatibility properties that
IB_Connection
> doesn't have.
>
> Incidentally, both TIB_Connection and TIBOQuery (through inheritance) have
> the Gen_ID() function, that does what your query does. Look up its
> arguments in the help text.
>
> Another tip: if you have a Before Insert trigger like this on the table:
>
> begin
> new.idfield = gen_id(lotidgen, 1);
> end
>
> ..then your trigger will fire when the insert is posted, regardless of
what
> you passed in the field. If you already got the next value via
> GeneratorLinks or Gen_ID() or, indeed, your query (above) then the
> generator will end up being multi-stepped.
>
> Modify the trigger to
>
> if (new.idfield is null) then
> new.idfield = gen_id(lotidgen, 1);
>
> Helen
>
>
>
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