> Look into the SELECT...FOR UPDATE... clause to read your records.
> The FOR UPDATE will lock them for you....
> Be carefule using this, since if too many records are locked, your
> RDBMS may escalate the record locks to table lock
> (you may not need a table lock if the records are not that
> many....).

This will not work with Firebird 1.0 due to MGA architecture. Record
will be locked only when it is modified. In Firebird 1.5 there is
special addition to this select. Correct me if I am wrong, but it is

SELECT ... FOR UPDATE WITH LOCK

But again, this FB 1.5 feature and it is in beta.

Best regards,
Roman Rokytskyy