## ORM - 


Benefits
- Cross database support
- Secure
- Easy to maintain


Common python ORMS
- Django ORM
- SQLAlchemy
- Flask-SQLAlchemy

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- Setup your virtual environment
- pipenv

Migration
- alembic


Commands used
##### alembic init alembic
 - Creates the Alembic directory and config files.
After alembic init edit env.py in alembic folder;
  - remove  '''target_metadata = None''' and add
  '''
  from app.models import Base
  target_metadata = Base.metadata
  '''
  depending on thr folder that has your models

Now fo to  alembic.ini file in the roort directory and change the database url to be for sqlite i.e sqlalchemy.url = sqlite:///./database.db


##### alembic revision --autogenerate -m "Add users table"
 - Detects model changes and creates a new migration script.
##### alembic upgrade head 
 - Applies the latest migration to the database.
##### alembic downgrade -1  
 -  Reverts the last migration.

##### alembic history 
 - Shows a list of all migration versions.