When A module need modification, how to keep the old data?

[witwall]

for example, I want to add a new table, I can directly modify the project, then re-generate the module, then re-active the module, right?

I tried in this way, the old table will lost everything.

If possible the system automatically rename the old table to another name, and can import the old data to new table?

Of course, as a programmer, I can rename the table manually, but it is really difficult for an end-user.

[goFrendiAsgard]

You can modify modules/example/controllers/Info.php and add new columns there. Then you need to modify the module version in modules/example/description.txt. No-CMS will automatically check this, and update the columns as necessary.