DB Migration workflow
Flask-Migrate is an extension that handles SQLAlchemy database migrations for Flask applications using Alembic. The database operations are made available through the Flask command-line interface or through the Flask-Script extension.
Full list of migration commands and flask-migrate documents can be found here.
Initialize migration repository
This command creates a python script that describe what changes will be done to our db.
Rollback migration (downgrade)
All migration commands preserve data in the DB.