What is the difference between using ORM and writing direct SQL queries for database operations?

ORM (Object-Relational Mapping) is a tool that allows working with a database through objects and methods of a programming language, instead of writing SQL queries directly.

Advantages of ORM:

• Speeds up development, as there is no need to write SQL manually.
• Provides abstraction from a specific DBMS, easing portability.
• Allows working with data in a familiar object-oriented style.

Disadvantages of ORM:

• Performance issues may arise with complex queries.
• It is not always possible to implement specific or optimized SQL queries.

Writing SQL queries directly gives full control over queries and optimization, but requires deep SQL knowledge and can increase code complexity.

Example of using ORM (SQLAlchemy in Python):

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:///example.db')
Session = sessionmaker(bind=engine)
session = Session()

# Adding a user
new_user = User(name='Alice')
session.add(new_user)
session.commit()

# Querying users
users = session.query(User).filter_by(name='Alice').all()

Thus, the choice between ORM and SQL depends on project requirements, team experience, and the need for optimization.