Auto Increment A Column With Hibernate

Question

I have this situation where I need to increment a non primary key column upon insert of every new record. This column is not a primary key. However it has unique constraint. How can I use Hibernate Annotations to accomplish auto increment of this particular column? I know it can be done quite easily for primary keys, but I want exactly same thing to be done for a non primary key column (meaning without using @Id annotation?)

--Thanks

Solution 1

As far as I can see, you can use the Hibernate specific annotation @Generated. Your field would look something like this:

@Generated(value="GenerationTime.INSERT")
@GenericGenerator(name="fieldGenerator", strategy="sequence")
private X field;

You can read the different types of strategies here.

I'm 90% sure that should work. If it doesn't then let me know.

Solution 2

I checked this and Hibernate allow only one auto column (per table) and it must be defined as a key.

In addition to primary key column If you try to use more than one auto column you will get the error :

[error] o.h.t.h.SchemaUpdate - Incorrect table definition; there can be only one auto column and it must be defined as a key.

You can use sequence or table-use as sequence and save the return value as seq.

simple example of table use as sequence:

@Entity(name = "T1")

@Table(name = "t1")

public  class T1 {

    @Id
    @GeneratedValue
    @Column(name = "c_id")
    private Long seqId;

    public Long getseqId() {
        return seqId;
    }

    public void setseqId(Long sId) {
        this.seqId= sId;
    }
}

Comments

[Stefan Falk]

Would you be so kind and take a look at this: stackoverflow.com/questions/29976363/… maybe you can help me here.

[Ace]

You are three years late in answering this question :) I have moved on to NoSQL Technologies completely.

[MD Ruhul Amin]

@Id means primary key and the answer expected for non-primary-key column.