How to update tables using SQL Alchemy ORM in python

Hi I am trying to update multiple tables with sql alchemy orm in python. I am new to sql alchemy orm. I wanted to make sure I am in the right direction how to properly query a table and update the tables using sql alchemy orm.

Here is what I am trying to accomplish according to this graph:

Here is my code

from cars.models import Cars
from cars.models import CarType
from cars.models import CarModel
from cars.models import CarItem, CarItemOther
from sqlalchemy import create_engine
from sqlalchemy.orm import session
from sqlalchemy.sql.expression import update
from sqlalchemy.sql.sqltypes import String, Text

# To update cars
def update_cars_models(session):
    db = session

    state = db.query(Cars).filter(Cars.state == "PRE_PROCESS").all()

    car_update = ()
    for row in state:
      if (row.state == "PRE_PROCESS"):
        car_update = CarType("Subaru", "WHITE", "PRE_PROCESS", Cars("Subaru", "PROCESS"))

        # update and commit
        update(car_update)
        db.commit()

    db.close()

    return car_update

# To update each car models
def update_cars(car_update, session):

    db = session
    cars = car_update

    cars_models = ()
    for row in cars:
      if (row.state == "PRE_PROCESS"):
        cars_models = CarModel("PRE_PROCESS", CarType("Subaru", "PROCESSED"), CarItem("PROCESSED", CarItemOther("Payment Processed")))
        
        # update and commit
        update(cars_models)
        db.commit()
    
    car_process = db.query(CarType).filter(CarType.state == "PROCESSED").all()
    cars_models_process = ()
    for row in car_process:
      if (row.state == "PROCESSED"):
        cars_models_process = CarModel("PROCESSED", CarType("Subaru", "PROCESSED"), CarItem("PROCESSED", CarItemOther("Payment Processed")))

        # update and commit
        update(cars_models_process)
        db.commit()

    # close session
    db.close()

    return cars_models
   
if __name__ == "__main__":
      
    # To update cars
    car_up = update_cars_models(session)
    update_cars(car_up, session)

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