Какие задачи выполнял с базами данных

import sqlite3
conn = sqlite3.connect('test.db')
cursor = conn.cursor()
cursor.execute("CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT)")
conn.commit()
conn.close()

import psycopg2
conn = psycopg2.connect(dbname='test', user='user', password='pass')
cursor = conn.cursor()
cursor.execute("SELECT * FROM users")
rows = cursor.fetchall()

from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()
class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)

engine = create_engine('sqlite:///test.db')
Session = sessionmaker(bind=engine)
session = Session()
user = User(name='Alice')
session.add(user)
session.commit()