Hibernate Auto Increment ID

I have a j2ee application using hibernate with annotation. How do I annotate the Id field in my pojo class to set it as auto increment or auto generated. and in adding the bean do I leave that field in my bean null?

Solution 1:

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int id;

and you leave it null (0) when persisting. (null if you use the Integer / Long wrappers)

In some cases the AUTO strategy is resolved to SEQUENCE rathen than to IDENTITY or TABLE, so you might want to manually set it to IDENTITY or TABLE (depending on the underlying database).

It seems SEQUENCE + specifying the sequence name worked for you.

Solution 2:

Do it as follows :-

@Id
@GenericGenerator(name="kaugen" , strategy="increment")
@GeneratedValue(generator="kaugen")
@Column(name="proj_id")
  public Integer getId() {
    return id;
 }

You can use any arbitrary name instead of kaugen. It worked well, I could see below queries on console

Hibernate: select max(proj_id) from javaproj
Hibernate: insert into javaproj (AUTH_email, AUTH_firstName, AUTH_lastName, projname,         proj_id) values (?, ?, ?, ?, ?)