<svein.erling.tysvaer@...> wrote:

>
> I doubt it. I'd simply add another table and let Firebird handle

duplicates:

1- Let's go back to a more primitive case:

CREATE TABLE TABLE1 (
PK BIGINT PRIMARY KEY,
F1 INTEGER NOT NULL UNIQUE);

Start transaction1, insert a new record with F1=1 (do not commit)
Start transaction2, insert a new record with F1=1. (do not commit)
The operation will fail although transaction2 is not supposed to see
the record of transaction1 since transaction1 is not committed).

2- Let's try a different constraint:

CREATE TABLE TABLE1 (
PK BIGINT PRIMARY KEY,
F1 INTEGER NOT NULL CHECK(NOT EXISTS(SELECT PK FROM TABLE1 WHERE
F1=F1)));

Start transaction1, insert a new record with F1=1 (do not commit)
Start transaction2, insert a new record with F1=1. (do not commit)
The operation will succeed.
Commit both transactions. The check constraint will be ignored.

Is this the correct behaviour?

"Dimitry Sibiryakov" <SD@...> wrote:

> These fields' values will be unique if they are gotten from one
> generator.

Sure.