Unique Constraint Over Multiple Columns

Question

I am using SEAM 2/Hibernate along with PostgreSQL 9 database. I have the following table

Active Band
===========
active_band_id serial
active_band_user text
acti         


        

Answer 1

There is no Hibernate annotation that checks uniqueness before insert/update. But there is annotation which will generate such a constraint to database if automatic database creation is used:

 @Table(
    name="ACTIVE_BAND", 
    uniqueConstraints=
        @UniqueConstraint(columnNames={"active_band_user", "active_band_date"})
)

Answer 2

In a more modern syntax, it would be :

@Table(
    name="ACTIVE_BAND", 
    uniqueConstraints =
        [UniqueConstraint(
                columnNames = ["active_band_user", "active_band_date"]
        )]
)