JPA or Hibernate to generate a (non primary key) column value, not starting from 1

Question

I want a JPA/Hibernate (preferably JPA) annotation that can generate the value of a column, that is not a primary key and it doesn't start from 1.

From what I have seen JPA cannot do that with @GeneratedValue and @SequenceGenerator and @TableGenerator. Or with anything else.

I have seen a solution with an extra table, which I find is not elegant.

I can live with a Hibernate annotation, because I already have hibernate annotations.

I want to use @Generated but I cannot make it work and people claim that it is possible.

@Generated(GenerationTime.INSERT)
private long invoiceNumber;//invoice number

Update: an extra requirement, if the transaction is rolled back, we can't have a gap in the numbering. Anyone?

Answer 1

The @GeneratedValue only works for identifiers and so you can't use it. If you use MySQL, you are quite limited, since database sequences are not supported.

InnoDB doesn't support multiple AUTO_INCREMENT columns and if your table PK is AUTO_INCREMENTED, then you have two options:

1. Go for a separate table that behaves like a sequence generator, the solution you already said you are not happy about.

2. Use an INSERT TRIGGER to increment that column.