How to perform database schema migration updates?

To update a database schema using migrations in Python, ORM tools like Django ORM or Alembic for SQLAlchemy are often used.

Example with Django:

1. Make changes to models (models.py).
2. Run the command to create migrations:

django-admin makemigrations

3. Apply migrations to the database:

django-admin migrate

This will create or update tables, fields, and relationships in the database according to the model changes.

In Alembic (for SQLAlchemy), the process is similar: create migration scripts and apply them using the command alembic upgrade.

Thus, migrations allow managing database schema changes in a sequential and safe manner.