Difference between "insertable=false" and "transient" in Hibernate

Question

The following code uses @Column annotation with insertable=false.

@Entity
public class UserDetails {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "User_Id")
    private int userId;

    @Column(name = "User_Name", insertable = false)
    private String userName;
}

While the following code uses @Transient annotation instead.

@Entity
public class UserDetails {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "User_Id")
    private int userId;

    @Transient
    private String userName;
}

In both cases, the column will not be created.

Are there any different functionalities between the 2 sample codes?

Answer 1

@Transient means: this attribute is not persistent at all. It's not handled by JPA. Every time you get an entity from the database, the attribute will be null (or whatever it's initialized to by the no-arg constructor).

insertable=false means that JPA won't include the column in the insert statement when saving the entity. But it will when updating the entity, and it will load it from the database.