Assigning sequence numbers treo cords

Question

Please help to understand the following, because it's a little unclear for me.. can you provide me an example?
So, regarding to assigning sequence numbers when a new record is created, we usually use a pre-insert trigger, with this code:
SELECT orders_seq.NEXTVAL
INTO :orders.order_id
FROM SYS.dual;
But:
You can also assign sequence numbers from a table. If you use this method, two transactional
triggers are usually involved:
• Use Pre-Insert to select the next available number from the sequence table (locking the row
to prevent other users from selecting the same value), assign it to the Forms item, and
increment the value in the sequence table by the required amount.
• Use Post-Insert to update the sequence table, recording the new upper value for the
sequence.So how to assign a sequence number from a ... table?
Thanks

Answer 1

You have to implement the number generator yourself; something similar to this: http://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:4343369880986
cheers