Question

I’m trying to implement an inherited structure for user types in my application.

@Entity
@Table(name="User_") // Need this since "User" is a reserved name in SQL Server
@Inheritance(strategy=InheritanceType.JOINED)
public class User extends Model {

    @Column(nullable=false,unique=true)
    public String username;

    ...
}

---

@Entity
public class Employee extends User {
    ...
}

---

@Entity
public class Client extends User {
    ...
}

---

When I do this, the Employee and Client tables that get created do not have any foreign keys to the User_ table, nor does the User_ table have any foreign keys to the Employee or Client tables. How can I make this happen?

Ideally, I’d like an Employee.username column that is a foreign key for User_, so I other tables can have references to Employee.username.

I’m using Play! Framework 1.2.5 and SQL Server 2005.

Answer 1

Answering my own question since it’s been a few days.

The first question I asked was:

When I do this, the Employee and Client tables that get created do not have any foreign keys to the User_ table, nor does the User_ table have any foreign keys to the Employee or Client tables. How can I make this happen?

This was answered in the comments, thanks axtavt! It turns out that id is the Primary Key and the Foreign Key.

---

Next up, I wrote this in my question:

Ideally, I’d like an Employee.username column that is a foreign key for User_, so I other tables can have references to Employee.username.

And clarified / worded as a question in comments:

Any way to actually have the username as a string show up in Employee? I want to be able to do this on other tables:

@ManyToOne
@JoinColumn(name="employee", referencedColumnName="username")
public Employee employee;

I was never able to find an adequate answer to this, so I’m making do with the default (using the numeric id field):

@ManyToOne
public Employee employee;

I’ll be happy to accept another answer if this can be solved.