What is ORM? Pros and cons?

ORM (Object-Relational Mapping) is a technology that allows working with a database through objects in a programming language, abstracting SQL queries.

Advantages of ORM:

• Accelerates development as it reduces the need to write extensive SQL code.
• Allows working with data in a familiar object-oriented style.
• Ensures portability across different DBMS.
• Helps avoid errors in SQL queries.

Disadvantages of ORM:

• May generate inefficient queries, reducing performance.
• Complex queries can be difficult to express through ORM.
• An additional layer of abstraction increases complexity and response time.

Example of using ORM in Python with SQLAlchemy:

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

Base = declarative_base()

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

engine = create_engine('sqlite:///:memory:')
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
session = Session()

new_user = User(name='Иван')
session.add(new_user)
session.commit()

user = session.query(User).filter_by(name='Иван').first()
print(user.name)  # Иван