The ID generator field will automatically create and store its running values in an environment variable in your app. If you remove a record, the running number in the environment variable will remain untouched.

In this case, you'll have to write bean shell code to handle this event when a record is removed. You can refer here on how to programmatically manipulate environment variable values: Manage Environment Variable using Form

Thank Chris , but like a link you share, I still can't figure it out, Do you have any more clues? I don't know much about Java, It's too hard for me to checked, please give me more information :((((( (If there is no other way than I have to learn Java)

Unfortunately I don't think there is any other way. But the guide's source codes are documented well.

But the guide 's source on your link is not right in my project. After that, all of my function is disable. I have to build my project again :(((