Hi,
I try to find a simple way to create the following relations:

User (abstract class) stores fields username, etc
Operator extends User (entity)
Client extends User (entity)

I want Operator and Client to be entities with different tables,

the inheritance examples presented in the doc are not working in this case because I also have many to many relations in the Operator and Client classes and an error occurs at deployment (many.. relations not supported with inherintance)

thanks a lot

Have you tried making the User class an @EmbeddableSuperclass ? This will actually make Operator and Client free from possible inheritance issues. Also it will be more beneficial to you if you post what versions of hibernate you are using, actual code and actual error messages. :)

I choosed another option:
I used
@Inheritance(strategy=InheritanceType.JOINED)

and also created the base class as a table,

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class User implements Serializable ...
... defined ID ...

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class Operator extends User...
... defined ID ...

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class Client extends User ...
... defined ID ...

this will generate 3 tables and the relations between them are managed using the matching of ids (in Operator and Client tables I will not have sequencial keys... but sets of keys, ex operator:1,3,10... client:2,4..9,..., user:1,2,...10

MISTAKE:

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class User implements Serializable ...
... defined ID ...

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class Operator extends User...

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class Client extends User ...

THE ID's are not redefined into the child classes...

anyway, your idea was very good, I'll use that annotation in other stuff. thanks a lot