A quick script using sqlalchemy for query development

sqlalchemy_example.py

from sqlalchemy import create_engine, MetaData
from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import sessionmaker


def create_sa_connection(connection_string):
    """ A nice helper function for creating the session and engine required
    for sqlalchemy interactions with the database.
    :param connection: 
    :return: 
    """
    engine = create_engine(connection, echo=False)
    Session = sessionmaker(bind=engine)
    session = Session()
    return engine, session

# The connection string for connecting to the database
connection_string = 'postgresql+psycopg2://db_user:db_password@localhost:5432/db'

# Get the engine and the session we need to use engine for core and session for orm
engine, session = create_sa_connection(connection_string)

# Reflect the database to allow for declarative and using core
Base = automap_base()
Base.prepare(engine, reflect=True)

# Create a class for a specific table
User = Base.classes.users

# Write a query to get those users
users = session.query(User).all()

# Display all the user emails in the Users table
for user in users:
    print(user.email)