I want to make sure that all rows in my table have a unique combination of two fields, and I want to specify this using annotations in my entity class. I have tried using a combination of @Table and @UniqueConstraint but apparently I'm doing it wrong, in that I can only seem to specify that the separate columns should be unique (I can already specify that using the @Column's unique property) rather than a combination of columns. For example I want a table which has fields A and B to contain only rows which have a unique combination of A and B. Neither field/column needs to be unique, it's the combination of the two which should be unique.
Here's what I've tried so far with no joy:
@Table(name = "MY_TABLE",
uniqueConstraints = @UniqueConstraint(columnNames =
{ "FIELD_A", "FIELD_B" }))
and
@Table(name = "MY_TABLE",
uniqueConstraints = { @UniqueConstraint(columnNames =
{ "FIELD_A", "FIELD_B" }) })
Can someone please suggest the right way to do this? Also if it's possible to use JPA annotations instead of Hibernate-specific annotations that'd be preferable.
Thanks in advance for your help.
--James