> > I need to update a group of records and while i do that no one
> > should read or update that group of record. The granularity of
> > the operation should not be at record level but at group of
> > records level. So i'm trying to acquire a table lock.
>
> Simply set transaction isolation level to TRANSACTION_SERIALIZABLE.

And one more solution. Instead of making SELECT ... FROM ...
WHERE ... FOR UPDATE (which does not work in FB 1.0) use UPDATE ...
SET any_field = any_field WHERE ... This will lock your set of
records without blocking the whole table. This method gives you
better performance than TRANSACTION_SERIALIZABLE because it can also
be used with TRANSACTION_REPEATABLE_READ and
TRANSACTION_READ_COMMITTED.

Best regards,
Roman Rokytskyy