Application Express :: Update Record In Another Row When Date Changed

As all of you know, In the Apex,  when you create a form with report in the page, you are able to insert and edit data. But when you edit the data, the data will be modified in the same row. In other word, you loose the old data.

What I need to do is: I have revised_num field and production_date field. I want to create a form with report and insert and edit data as is in the apex and insert 0 to the revised num until production date is null. But when  production date is not null, then from that point, I want to insert data to another row and modify revised num to 1. and I want the revised num be incremented by 1 each time the user modifies the data after the production date is not null.I don't know where I should start.