You need to use a generator to obtain unique values to use as primary key
values.
If you want to maintain a serial line of numbers with no holes, there is a
tech info sheet on my web-site that will help. This isn't easy to accomplish
with an optimistic locking database like Firebird/InterBase.

Jason Wharton

----- Original Message -----
From: "ronald_greven" <ronald_greven@...>
To: <IBObjects@yahoogroups.com>
Sent: Wednesday, November 05, 2003 3:35 AM
Subject: [IBO] Problems with TIB_Transaction


> 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