> I'm using Firebird-1.5.2.4731 an IBX 7.08 drivers in a Delphi

application.

This is irrelevant to your problem.

>
> Occasionally I get a deadlock situation with the following message:
>
> Lock conflict on no wait transaction. Deadlock. Update conflicts

with concurrent update.

> SQL Code: -901
> IB Error Number: 33 55 44 345
>
> What is causing it and how do I avoid it?
>

Here is an easier way to duplicate it. Open two iSQL windows connected
to the same database, and run an identical update query in both
windows without committing, voila.

This is caused because the transactions is trying to update or delete
a record that has already been updated or deleted by a transaction
that was not committed before your transaction started. It is an
exception you should allow for and expect to happen if you have
multiple transactions potentially interested in the same record.

By the way, the update or delete can be explicit or implicit. In other
words, you may only insert a record into a table, but if that table
has an insert trigger that updates or deletes a record, then this
could also cause the conflict.

Adam