Change BASE_DIR in django settings to up a directory

Question

I am working on django project in which I tried to setup multiple settings files and now I am getting database migrations error/notification .I dont want to create new db and use the previous one .
Previous dir Structure

|myproject
|-myproject
|--settings.py
|-db

and in my base.py BASE_DIR = Path(__file__).resolve().parent.parent
Current Dir

|myproject
|-myproject
|--db(new db after running sever)
|--settings
|---base.py
|---development.py
|-db(old db)

I dont how base_dir thing works .I want to use my old db and all other stuff .I tried google but I dont understand anything there.so how to I up one dir my BASE_DIR path .
Thanks in advance any advice will be helpful.