Can you tell the advantages and disadvantages of ORM, and when would you use or not use it?

Advantages of ORM:

• Simplifies working with the database by allowing you to work with objects instead of SQL queries.
• Improves code readability and maintainability.
• Allows abstraction from a specific DBMS, easing portability.
• Automates many routine operations (e.g., mapping, caching).

Disadvantages of ORM:

• Potentially reduces performance due to an additional layer of abstraction.
• Complex queries and optimizations can be difficult or impossible through ORM.
• Sometimes leads to inefficient SQL queries (N+1 problem).
• Steep learning curve for complex ORM features.

When to use:

• When developing typical CRUD applications with simple or medium complexity business logic.
• When speed of development and maintainability are important.

When not to use:

• In high-load systems where performance and query optimization are critical.
• For complex analytical queries requiring fine-tuned SQL.
• If the team is proficient in SQL and ready to write optimized queries manually.

Example of ORM usage in Java with Hibernate:

@Entity
public class User {
    @Id
    private Long id;
    private String name;
    // getters and setters
}

// Fetching a user
User user = session.get(User.class, userId);