Subject Solving Concurrency Inserting Record, Is it Possible ?
Author ferry_new2004
Hi friends, I have java codes to do single task, that is to insert a
record into table A which
fields name are id, code, name.
the field Id is set by firebird through trigger so that the id will
always be unique.

When the java code is run, it will insert table A with
value 1,'CODE1','NAME'

This code has no problem when the program is run by single user.
But if 3 users trying to run the code (from different computers), the
result is
three records are inserted. They are


How to make the two other users fail inserting the record while the
first time user inserting the record successful ?
If I lock the table, it means the program can only work in single user
mode. In fact, I have never tried the Firebird feature locking table. :)

I have tried to use trigger AFTER INSERT to check whether any record
has been inserted or not. If any record has been inserted, it will
throw firebird exception. But it seems that The trigger AFTER INSERT
can only detect inserted record after the other transaction commit
first. It means that the problem cannot be solved using trigger AFTER

I have search the mailing list message but problem like this has never
been discussed. Or do I missing some discussion ? :D

Is there any better way to solve this problem ?

Thank you & regards,