ORM stands for Object-Relational Mapping — a programming technique that automatically maps objects in your application code to rows in a relational database table, and vice versa.
🔹 How it works:
- You define Java (or any language’s) classes called entities, with fields like
name,email, etc. - Each entity is mapped to a table, and each field maps to a column.
- The ORM framework automatically handles converting between objects and database records (known as object-relational impedance mismatch).
🔹 Key benefits of ORM:
✅ Eliminates most repetitive SQL and JDBC code.
✅ Lets you work in an object-oriented way — persisting, retrieving, and updating objects directly.
✅ Handles relationships (e.g., one-to-many, many-to-many) naturally through associations.
✅ Supports features like caching, lazy loading, cascading, and inheritance mapping.
✅ Reduces human error by avoiding manual SQL for standard CRUD operations.
🔹 Example with Hibernate:
Your User Java class maps to a users table:
@Entity
@Table(name = "users")
public class User {
@Id
private Long id;
private String username;
private String email;
}
Hibernate ORM will automatically generate the necessary SQL statements behind the scenes to insert, update, delete, or query User objects.
✅ Key takeaway:
ORM bridges the gap between your object-oriented code and relational databases — saving time, reducing bugs, and improving maintainability.