Hi Set,

many thanks. This helps me a lot. But there is another problem,
nearly the same as the one I had, but I cant use a generator there,
cause this is a table, from a database, where another software is
working with, so I cant change the field-stucture.

tablename : documents
the unique index is : doctype, docart, posnr

before inserting a record, i need to start a sql, cause a user in the
other software could inserted a new record :
select max(posnr) as maxvalue from documents
where doctype = 'L'
and docart = 'A';

then I have to increase this value and insert a new record.

The problem is the same. User A, and User B insert a record in table
documents.

Is there maybe anyway a change to work with a generator, or what
could I do else?

Best greetings

Ronni


--- In IBObjects@yahoogroups.com, "Svein Erling"
<svein.erling.tysvaer@k...> wrote:

> Hi Ronni,
> the standard way of ensuring uniqueness, is to use generators. That
> is, change your procedure to
>
> > now there is a loop, for user A : 1 to 100
> > - get ticketnumber: ticketnumber = GEN_ID(<generator_name>, 1)
> > - //do not use increment, it always cause problems in a multiuser
> environment
> > - write new record in table ticketpos (ticketnumber 100001)
>
> This does not ensure the ticketnumbers for user A to be

consecutive,

> you may end up with user A getting ticket numbers 100001 and

100003,

> whereas user B may get ticket number 100002, and in case of

rollback

> you may encounter numbers that are not used at all. However, you

will

> never experience duplicate keys.
>
> http://www.ibobjects.com/docs/ti_AuditableSeries.ZIP may also give

you

> some useful information, depending on what you are trying to do.
>
> Hope this helps,
> Set
>
> --- In IBObjects@yahoogroups.com, "ronald_greven"

<ronald_greven@y...>

> wrote:
> > Hi,
> >
> > First of all, sorry about my bad english, I hope you understand,
> > which problem I have.
> >
> > I have a big problem.
> >
> > I use IB_Objects with a firebird database. Its an multiuser-
> > environment.
> > There is a table called tickets with only one row.
> >
> > number ticketnumber
> > 1 1000000
> >
> > in a one-user environment, no problem.
> > But :
> >
> > Input (User A) : A amount of 100
> > Input (User B) : A amount of 300
> >
> > now there is a loop, for user A : 1 to 100
> > - get ticketnumber
> > - inc ticketnumber with 1
> > - write new record in table ticketpos (ticketnumber 100001)
> > - write back new ticketnumber in table ticketpos
> >
> > in table ticketpos the unique index is for the ticketnumber
> >
> > the same loop for user B : 1 to 300
> >
> > there are 2 active transactions. Each increase the value
> ticketnumber
> > with 1 and write it back.
> > now a error occurs : attempt to store duplicate value visible to
> > active transaction....
> >
> > how can i let one transaction wait (ex. user A) for the commit of
> the
> > other active transaction (user B)?
> >
> > Wow, that was hard to explain. But I hope, you can help me...
> >
> > Best regards
> >
> > Ronni