DAO vs DTO

Feature	DAO (Data Access Object)	DTO (Data Transfer Object)
Purpose	Manages database operations	Transfers data between layers
Contains Business Logic?	Yes (CRUD operations)	No
Interacts with Database?	Yes	No
Used in	Persistence layer	API layer, service layer
Best For	Encapsulating database access	Controlling data exposure

Can DAO and DTO Be Used Together?

Yes, DAO and DTO are often used together in layered architectures.

Example: DAO and DTO in a Service Layer (Java Spring Boot)

@Service
public class UserService {
    private final UserDAO userDAO;
 
    public UserService(UserDAO userDAO) {
        this.userDAO = userDAO;
    }
 
    public UserDTO getUserById(int id) {
        User user = userDAO.findById(id);
        return new UserDTO(user.getId(), user.getName(), user.getEmail());
    }
}

In this example, UserDAO fetches the user from the database, while UserDTO ensures that only necessary fields are sent to the client.